21684297406464 has 288 divisors, whose sum is σ = 78081956709120. Its totient is φ = 5632284672000.

The previous prime is 21684297406441. The next prime is 21684297406501. The reversal of 21684297406464 is 46460479248612.

21684297406464 is a `hidden beast` number, since 2 + 1 + 6 + 8 + 42 + 97 + 40 + 6 + 464 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6220012 + ... + 9058539.

It is an arithmetic number, because the mean of its divisors is an integer number (271117905240).

Almost surely, 2^{21684297406464} is an apocalyptic number.

21684297406464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21684297406464 is an abundant number, since it is smaller than the sum of its proper divisors (56397659302656).

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

21684297406464 is a wasteful number, since it uses less digits than its factorization.

21684297406464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15278597 (or 15278574 counting only the distinct ones).

The product of its (nonzero) digits is 111476736, while the sum is 63.

The spelling of 21684297406464 in words is "twenty-one trillion, six hundred eighty-four billion, two hundred ninety-seven million, four hundred six thousand, four hundred sixty-four".