21665470464 has 480 divisors, whose sum is σ = 73063710720. Its totient is φ = 6336921600.

The previous prime is 21665470457. The next prime is 21665470483. The reversal of 21665470464 is 46407456612.

21665470464 is a `hidden beast` number, since 2 + 1 + 66 + 547 + 0 + 46 + 4 = 666.

It is a super-2 number, since 2×21665470464² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 56567617 + ... + 56567999.

It is an arithmetic number, because the mean of its divisors is an integer number (152216064).

Almost surely, 2^21665470464 is an apocalyptic number.

21665470464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21665470464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36531855360).

21665470464 is an abundant number, since it is smaller than the sum of its proper divisors (51398240256).

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

21665470464 is a wasteful number, since it uses less digits than its factorization.

21665470464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 459 (or 430 counting only the distinct ones).

The product of its (nonzero) digits is 967680, while the sum is 45.

The spelling of 21665470464 in words is "twenty-one billion, six hundred sixty-five million, four hundred seventy thousand, four hundred sixty-four".