21011031504 has 80 divisors (see below), whose sum is σ = 60709031040. Its totient is φ = 6957273600.

The previous prime is 21011031487. The next prime is 21011031523. The reversal of 21011031504 is 40513011012.

21011031504 is a `hidden beast` number, since 21 + 0 + 110 + 31 + 504 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 95817 + ... + 226280.

It is an arithmetic number, because the mean of its divisors is an integer number (758862888).

Almost surely, 2^21011031504 is an apocalyptic number.

21011031504 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21011031504 is an abundant number, since it is smaller than the sum of its proper divisors (39697999536).

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

21011031504 is a wasteful number, since it uses less digits than its factorization.

21011031504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322265 (or 322253 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

Adding to 21011031504 its reverse (40513011012), we get a palindrome (61524042516).

The spelling of 21011031504 in words is "twenty-one billion, eleven million, thirty-one thousand, five hundred four".