21012503544 has 64 divisors (see below), whose sum is σ = 59088708000. Its totient is φ = 7004162016.

The previous prime is 21012503527. The next prime is 21012503549. The reversal of 21012503544 is 44530521012.

21012503544 is a `hidden beast` number, since 2 + 101 + 2 + 503 + 54 + 4 = 666.

It is a super-2 number, since 2×21012503544² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012503549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 582999 + ... + 617990.

Almost surely, 2^21012503544 is an apocalyptic number.

21012503544 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21012503544 is an abundant number, since it is smaller than the sum of its proper divisors (38076204456).

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

21012503544 is an equidigital number, since it uses as much as digits as its factorization.

21012503544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1201016 (or 1200994 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

The spelling of 21012503544 in words is "twenty-one billion, twelve million, five hundred three thousand, five hundred forty-four".