21391770815999 has 8 divisors (see below), whose sum is σ = 21941666920800. Its totient is φ = 20847292407136.

The previous prime is 21391770815951. The next prime is 21391770816043. The reversal of 21391770815999 is 99951807719312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21391770815999 - 2²⁸ = 21391502380543 is a prime.

It is a super-3 number, since 3×21391770815999³ (a number of 41 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21391770815929) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1354415987 + ... + 1354431780.

It is an arithmetic number, because the mean of its divisors is an integer number (2742708365100).

Almost surely, 2^{21391770815999} is an apocalyptic number.

21391770815999 is a deficient number, since it is larger than the sum of its proper divisors (549896104801).

21391770815999 is a wasteful number, since it uses less digits than its factorization.

21391770815999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2708847969.

The product of its (nonzero) digits is 77157360, while the sum is 71.

The spelling of 21391770815999 in words is "twenty-one trillion, three hundred ninety-one billion, seven hundred seventy million, eight hundred fifteen thousand, nine hundred ninety-nine".