21662540 has 24 divisors (see below), whose sum is σ = 46551120. Its totient is φ = 8463168.

The previous prime is 21662533. The next prime is 21662567. The reversal of 21662540 is 4526612.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11735 + ... + 13454.

It is an arithmetic number, because the mean of its divisors is an integer number (1939630).

Almost surely, 2^21662540 is an apocalyptic number.

21662540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21662540 is an abundant number, since it is smaller than the sum of its proper divisors (24888580).

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

21662540 is a wasteful number, since it uses less digits than its factorization.

21662540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25241 (or 25239 counting only the distinct ones).

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

The square root of 21662540 is about 4654.3033850406. The cubic root of 21662540 is about 278.7638534007.

The spelling of 21662540 in words is "twenty-one million, six hundred sixty-two thousand, five hundred forty".