21785608767 has 32 divisors (see below), whose sum is σ = 31599025920. Its totient is φ = 13271132160.

The previous prime is 21785608703. The next prime is 21785608771. The reversal of 21785608767 is 76780658712.

It is not a de Polignac number, because 21785608767 - 2⁶ = 21785608703 is a prime.

It is a super-2 number, since 2×21785608767² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21785608667) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2135583 + ... + 2145759.

It is an arithmetic number, because the mean of its divisors is an integer number (987469560).

Almost surely, 2^21785608767 is an apocalyptic number.

21785608767 is a deficient number, since it is larger than the sum of its proper divisors (9813417153).

21785608767 is a wasteful number, since it uses less digits than its factorization.

21785608767 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10743.

The product of its (nonzero) digits is 7902720, while the sum is 57.

The spelling of 21785608767 in words is "twenty-one billion, seven hundred eighty-five million, six hundred eight thousand, seven hundred sixty-seven".