21686929165 has 8 divisors (see below), whose sum is σ = 28390161888. Its totient is φ = 15772312080.

The previous prime is 21686929157. The next prime is 21686929193. The reversal of 21686929165 is 56192968612.

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

It is not a de Polignac number, because 21686929165 - 2³ = 21686929157 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (55), and also a Moran number because the ratio is a prime number: 394307803 = 21686929165 / (2 + 1 + 6 + 8 + 6 + 9 + 2 + 9 + 1 + 6 + 5).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 197153847 + ... + 197153956.

It is an arithmetic number, because the mean of its divisors is an integer number (3548770236).

Almost surely, 2^21686929165 is an apocalyptic number.

It is an amenable number.

21686929165 is a deficient number, since it is larger than the sum of its proper divisors (6703232723).

21686929165 is a wasteful number, since it uses less digits than its factorization.

21686929165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 394307819.

The product of its digits is 2799360, while the sum is 55.

The spelling of 21686929165 in words is "twenty-one billion, six hundred eighty-six million, nine hundred twenty-nine thousand, one hundred sixty-five".