21716540 has 12 divisors (see below), whose sum is σ = 45604776. Its totient is φ = 8686608.

The previous prime is 21716533. The next prime is 21716567. The reversal of 21716540 is 4561712.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 542894 + ... + 542933.

It is an arithmetic number, because the mean of its divisors is an integer number (3800398).

Almost surely, 2^21716540 is an apocalyptic number.

21716540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21716540 is an abundant number, since it is smaller than the sum of its proper divisors (23888236).

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

21716540 is a wasteful number, since it uses less digits than its factorization.

21716540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1085836 (or 1085834 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 21716540 is about 4660.1008572777. The cubic root of 21716540 is about 278.9952937461.

The spelling of 21716540 in words is "twenty-one million, seven hundred sixteen thousand, five hundred forty".