31012210021 has 4 divisors (see below), whose sum is σ = 33397764652. Its totient is φ = 28626655392.

The previous prime is 31012210013. The next prime is 31012210051. The reversal of 31012210021 is 12001221013.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12901779396 + 18110430625 = 113586^2 + 134575^2 .

It is a cyclic number.

It is not a de Polignac number, because 31012210021 - 2³ = 31012210013 is a prime.

It is a super-2 number, since 2×31012210021² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (13), and also a Moran number because the ratio is a prime number: 2385554617 = 31012210021 / (3 + 1 + 0 + 1 + 2 + 2 + 1 + 0 + 0 + 2 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31012209983 and 31012210010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31012210051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1192777296 + ... + 1192777321.

It is an arithmetic number, because the mean of its divisors is an integer number (8349441163).

Almost surely, 2^31012210021 is an apocalyptic number.

It is an amenable number.

31012210021 is a deficient number, since it is larger than the sum of its proper divisors (2385554631).

31012210021 is a wasteful number, since it uses less digits than its factorization.

31012210021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2385554630.

The product of its (nonzero) digits is 24, while the sum is 13.

Adding to 31012210021 its reverse (12001221013), we get a palindrome (43013431034).

It can be divided in two parts, 3101 and 2210021, that added together give a palindrome (2213122).

The spelling of 31012210021 in words is "thirty-one billion, twelve million, two hundred ten thousand, twenty-one".