31000021021 has 8 divisors (see below), whose sum is σ = 31603941720. Its totient is φ = 30396804672.

The previous prime is 31000020983. The next prime is 31000021037. The reversal of 31000021021 is 12012000013.

It can be written as a sum of positive squares in 4 ways, for example, as 6766872121 + 24233148900 = 82261^2 + 155670^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 31000021021 - 2¹⁹ = 30999496733 is a prime.

It is a super-2 number, since 2×31000021021² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31000020989 and 31000021007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31000021081) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 86770 + ... + 263683.

It is an arithmetic number, because the mean of its divisors is an integer number (3950492715).

Almost surely, 2^31000021021 is an apocalyptic number.

It is an amenable number.

31000021021 is a deficient number, since it is larger than the sum of its proper divisors (603920699).

31000021021 is a wasteful number, since it uses less digits than its factorization.

31000021021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 352175.

The product of its (nonzero) digits is 12, while the sum is 10.

Adding to 31000021021 its reverse (12012000013), we get a palindrome (43012021034).

The spelling of 31000021021 in words is "thirty-one billion, twenty-one thousand, twenty-one".