21021220431 has 24 divisors (see below), whose sum is σ = 30932410080. Its totient is φ = 13752849600.

The previous prime is 21021220411. The next prime is 21021220481. The reversal of 21021220431 is 13402212012.

It is a happy number.

21021220431 is a `hidden beast` number, since 2 + 1 + 0 + 212 + 20 + 431 = 666.

It is not a de Polignac number, because 21021220431 - 2¹⁰ = 21021219407 is a prime.

It is a super-2 number, since 2×21021220431² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021220411) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 197401 + ... + 284621.

It is an arithmetic number, because the mean of its divisors is an integer number (1288850420).

Almost surely, 2^21021220431 is an apocalyptic number.

21021220431 is a deficient number, since it is larger than the sum of its proper divisors (9911189649).

21021220431 is a wasteful number, since it uses less digits than its factorization.

21021220431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87727 (or 87724 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

Adding to 21021220431 its reverse (13402212012), we get a palindrome (34423432443).

The spelling of 21021220431 in words is "twenty-one billion, twenty-one million, two hundred twenty thousand, four hundred thirty-one".