21231221031 has 12 divisors (see below), whose sum is σ = 30670538808. Its totient is φ = 14152661424.

The previous prime is 21231221017. The next prime is 21231221113. The reversal of 21231221031 is 13012213212.

It is not a de Polignac number, because 21231221031 - 2¹³ = 21231212839 is a prime.

It is a super-2 number, since 2×21231221031² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21231220995 and 21231221013.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21231221831) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29560 + ... + 208173.

It is an arithmetic number, because the mean of its divisors is an integer number (2555878234).

Almost surely, 2^21231221031 is an apocalyptic number.

21231221031 is a deficient number, since it is larger than the sum of its proper divisors (9439317777).

21231221031 is a wasteful number, since it uses less digits than its factorization.

21231221031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 247662 (or 247659 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21231221031 its reverse (13012213212), we get a palindrome (34243434243).

The spelling of 21231221031 in words is "twenty-one billion, two hundred thirty-one million, two hundred twenty-one thousand, thirty-one".