21637968665493 has 16 divisors (see below), whose sum is σ = 28922930562240. Its totient is φ = 14389202830464.

The previous prime is 21637968665477. The next prime is 21637968665497. The reversal of 21637968665493 is 39456686973612.

It is not a de Polignac number, because 21637968665493 - 2⁴ = 21637968665477 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21637968665497) 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, 3399496 + ... + 7404897.

It is an arithmetic number, because the mean of its divisors is an integer number (1807683160140).

Almost surely, 2^{21637968665493} is an apocalyptic number.

It is an amenable number.

21637968665493 is a deficient number, since it is larger than the sum of its proper divisors (7284961896747).

21637968665493 is a wasteful number, since it uses less digits than its factorization.

21637968665493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10806068.

The product of its digits is 2116316160, while the sum is 75.

The spelling of 21637968665493 in words is "twenty-one trillion, six hundred thirty-seven billion, nine hundred sixty-eight million, six hundred sixty-five thousand, four hundred ninety-three".