21155431044 has 24 divisors (see below), whose sum is σ = 53850188448. Its totient is φ = 6410736640.

The previous prime is 21155431039. The next prime is 21155431049. The reversal of 21155431044 is 44013455112.

It is an interprime number because it is at equal distance from previous prime (21155431039) and next prime (21155431049).

It is not an unprimeable number, because it can be changed into a prime (21155431049) 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, 80134077 + ... + 80134340.

It is an arithmetic number, because the mean of its divisors is an integer number (2243757852).

Almost surely, 2^21155431044 is an apocalyptic number.

It is an amenable number.

21155431044 is an abundant number, since it is smaller than the sum of its proper divisors (32694757404).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21155431044 is a wasteful number, since it uses less digits than its factorization.

21155431044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160268435 (or 160268433 counting only the distinct ones).

The product of its (nonzero) digits is 9600, while the sum is 30.

Adding to 21155431044 its reverse (44013455112), we get a palindrome (65168886156).

The spelling of 21155431044 in words is "twenty-one billion, one hundred fifty-five million, four hundred thirty-one thousand, forty-four".