21720486 has 16 divisors (see below), whose sum is σ = 44365824. Its totient is φ = 7086024.

The previous prime is 21720481. The next prime is 21720499. The reversal of 21720486 is 68402712.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21720481) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38230 + ... + 38793.

It is an arithmetic number, because the mean of its divisors is an integer number (2772864).

Almost surely, 2^21720486 is an apocalyptic number.

21720486 is an abundant number, since it is smaller than the sum of its proper divisors (22645338).

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

21720486 is a wasteful number, since it uses less digits than its factorization.

21720486 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77075.

The product of its (nonzero) digits is 5376, while the sum is 30.

The square root of 21720486 is about 4660.5242194414. The cubic root of 21720486 is about 279.0121909859.

The spelling of 21720486 in words is "twenty-one million, seven hundred twenty thousand, four hundred eighty-six".