21057813503 has 4 divisors (see below), whose sum is σ = 21266306808. Its totient is φ = 20849320200.

The previous prime is 21057813493. The next prime is 21057813509. The reversal of 21057813503 is 30531875012.

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 21057813503 - 2⁸ = 21057813247 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21057813509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 104246501 + ... + 104246702.

It is an arithmetic number, because the mean of its divisors is an integer number (5316576702).

Almost surely, 2^21057813503 is an apocalyptic number.

21057813503 is a deficient number, since it is larger than the sum of its proper divisors (208493305).

21057813503 is a wasteful number, since it uses less digits than its factorization.

21057813503 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208493304.

The product of its (nonzero) digits is 25200, while the sum is 35.

The spelling of 21057813503 in words is "twenty-one billion, fifty-seven million, eight hundred thirteen thousand, five hundred three".