21665464240 has 80 divisors (see below), whose sum is σ = 57601938240. Its totient is φ = 7423810560.

The previous prime is 21665464199. The next prime is 21665464283. The reversal of 21665464240 is 4246456612.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 21665464193 and 21665464202.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1031766 + ... + 1052554.

It is an arithmetic number, because the mean of its divisors is an integer number (720024228).

Almost surely, 2^21665464240 is an apocalyptic number.

21665464240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21665464240 is an abundant number, since it is smaller than the sum of its proper divisors (35936474000).

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

21665464240 is a wasteful number, since it uses less digits than its factorization.

21665464240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22670 (or 22664 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 40.

The spelling of 21665464240 in words is "twenty-one billion, six hundred sixty-five million, four hundred sixty-four thousand, two hundred forty".