21820825464 has 64 divisors (see below), whose sum is σ = 55750343040. Its totient is φ = 7114673280.

The previous prime is 21820825427. The next prime is 21820825471. The reversal of 21820825464 is 46452802812.

It is a super-2 number, since 2×21820825464² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 395119 + ... + 446945.

It is an arithmetic number, because the mean of its divisors is an integer number (871099110).

Almost surely, 2^21820825464 is an apocalyptic number.

21820825464 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 21820825464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27875171520).

21820825464 is an abundant number, since it is smaller than the sum of its proper divisors (33929517576).

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

21820825464 is a wasteful number, since it uses less digits than its factorization.

21820825464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52220 (or 52216 counting only the distinct ones).

The product of its (nonzero) digits is 245760, while the sum is 42.

The spelling of 21820825464 in words is "twenty-one billion, eight hundred twenty million, eight hundred twenty-five thousand, four hundred sixty-four".