21625440 has 48 divisors (see below), whose sum is σ = 68121648. Its totient is φ = 5766656.

The previous prime is 21625397. The next prime is 21625453. The reversal of 21625440 is 4452612.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21625440.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22047 + ... + 23006.

It is an arithmetic number, because the mean of its divisors is an integer number (1419201).

Almost surely, 2^21625440 is an apocalyptic number.

21625440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21625440 is an abundant number, since it is smaller than the sum of its proper divisors (46496208).

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

21625440 is a wasteful number, since it uses less digits than its factorization.

21625440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45071 (or 45063 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 24.

The square root of 21625440 is about 4650.3161182870. The cubic root of 21625440 is about 278.6046223243.

The spelling of 21625440 in words is "twenty-one million, six hundred twenty-five thousand, four hundred forty".