21686685696 has 351 divisors, whose sum is σ = 69001303449. Its totient is φ = 6559727616.

The previous prime is 21686685679. The next prime is 21686685701. The reversal of 21686685696 is 69658668612.

The square root of 21686685696 is 147264.

It is a perfect power (a square), and thus also a powerful number.

21686685696 is a `hidden beast` number, since 2 + 1 + 6 + 8 + 6 + 68 + 569 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 3208089600 + 18478596096 = 56640^2 + 135936^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 367570915 + ... + 367570973.

Almost surely, 2^21686685696 is an apocalyptic number.

21686685696 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21686685696 is the 147264-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21686685696

21686685696 is an abundant number, since it is smaller than the sum of its proper divisors (47314617753).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21686685696 is an equidigital number, since it uses as much as digits as its factorization.

21686685696 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174 (or 77 counting only the distinct ones).

The product of its digits is 44789760, while the sum is 63.

The spelling of 21686685696 in words is "twenty-one billion, six hundred eighty-six million, six hundred eighty-five thousand, six hundred ninety-six".