21786415078464 has 63 divisors (see below), whose sum is σ = 62447146257223. Its totient is φ = 7262101018752.

The previous prime is 21786415078453. The next prime is 21786415078471. The reversal of 21786415078464 is 46487051468712.

The square root of 21786415078464 is 4667592.

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

21786415078464 is a `hidden beast` number, since 2 + 1 + 7 + 8 + 6 + 41 + 507 + 84 + 6 + 4 = 666.

It is a super-2 number, since 2×21786415078464² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 111924967 + ... + 112119449.

Almost surely, 2^{21786415078464} is an apocalyptic number.

21786415078464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

21786415078464 is the 4667592-nd square number.

It is an amenable number.

21786415078464 is an abundant number, since it is smaller than the sum of its proper divisors (40660731178759).

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

21786415078464 is an frugal number, since it uses more digits than its factorization.

21786415078464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 388984 (or 194488 counting only the distinct ones).

The product of its (nonzero) digits is 72253440, while the sum is 63.

The spelling of 21786415078464 in words is "twenty-one trillion, seven hundred eighty-six billion, four hundred fifteen million, seventy-eight thousand, four hundred sixty-four".