21228708031 has 4 divisors (see below), whose sum is σ = 21246067152. Its totient is φ = 21211348912.

The previous prime is 21228707957. The next prime is 21228708041. The reversal of 21228708031 is 13080782212.

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

It is a cyclic number.

It is not a de Polignac number, because 21228708031 - 2²⁵ = 21195153599 is a prime.

It is a super-2 number, since 2×21228708031² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21228708041) 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, 8677726 + ... + 8680171.

It is an arithmetic number, because the mean of its divisors is an integer number (5311516788).

Almost surely, 2^21228708031 is an apocalyptic number.

21228708031 is a deficient number, since it is larger than the sum of its proper divisors (17359121).

21228708031 is a wasteful number, since it uses less digits than its factorization.

21228708031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17359120.

The product of its (nonzero) digits is 10752, while the sum is 34.

The spelling of 21228708031 in words is "twenty-one billion, two hundred twenty-eight million, seven hundred eight thousand, thirty-one".