21625640 has 32 divisors (see below), whose sum is σ = 49697280. Its totient is φ = 8465472.

The previous prime is 21625633. The next prime is 21625661. The reversal of 21625640 is 4652612.

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 7 ways as a sum of consecutive naturals, for example, 3872 + ... + 7631.

It is an arithmetic number, because the mean of its divisors is an integer number (1553040).

Almost surely, 2^21625640 is an apocalyptic number.

21625640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21625640 is an abundant number, since it is smaller than the sum of its proper divisors (28071640).

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

21625640 is a wasteful number, since it uses less digits than its factorization.

21625640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11561 (or 11557 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 21625640 is about 4650.3376221518. The cubic root of 21625640 is about 278.6054812009.

The spelling of 21625640 in words is "twenty-one million, six hundred twenty-five thousand, six hundred forty".