21056172503 has 16 divisors (see below), whose sum is σ = 22517913600. Its totient is φ = 19640406720.

The previous prime is 21056172499. The next prime is 21056172517. The reversal of 21056172503 is 30527165012.

It is a cyclic number.

It is not a de Polignac number, because 21056172503 - 2² = 21056172499 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21056172503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21056172583) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2937638 + ... + 2944796.

It is an arithmetic number, because the mean of its divisors is an integer number (1407369600).

Almost surely, 2^21056172503 is an apocalyptic number.

21056172503 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

21056172503 is a deficient number, since it is larger than the sum of its proper divisors (1461741097).

21056172503 is a wasteful number, since it uses less digits than its factorization.

21056172503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10342.

The product of its (nonzero) digits is 12600, while the sum is 32.

The spelling of 21056172503 in words is "twenty-one billion, fifty-six million, one hundred seventy-two thousand, five hundred three".