21085752987983 has 4 divisors (see below), whose sum is σ = 21093834919680. Its totient is φ = 21077671056288.

The previous prime is 21085752987973. The next prime is 21085752987997. The reversal of 21085752987983 is 38978925758012.

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 21085752987983 - 2¹² = 21085752983887 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 21085752987983.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21085752987973) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4040961935 + ... + 4040967152.

It is an arithmetic number, because the mean of its divisors is an integer number (5273458729920).

Almost surely, 2^{21085752987983} is an apocalyptic number.

21085752987983 is a deficient number, since it is larger than the sum of its proper divisors (8081931697).

21085752987983 is an equidigital number, since it uses as much as digits as its factorization.

21085752987983 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8081931696.

The product of its (nonzero) digits is 609638400, while the sum is 74.

The spelling of 21085752987983 in words is "twenty-one trillion, eighty-five billion, seven hundred fifty-two million, nine hundred eighty-seven thousand, nine hundred eighty-three".