21988568 has 32 divisors (see below), whose sum is σ = 47308800. Its totient is φ = 9385632.

The previous prime is 21988559. The next prime is 21988573. The reversal of 21988568 is 86588912.

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, 16553 + ... + 17831.

It is an arithmetic number, because the mean of its divisors is an integer number (1478400).

Almost surely, 2^21988568 is an apocalyptic number.

21988568 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21988568 is an abundant number, since it is smaller than the sum of its proper divisors (25320232).

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

21988568 is a wasteful number, since it uses less digits than its factorization.

21988568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1599 (or 1595 counting only the distinct ones).

The product of its digits is 276480, while the sum is 47.

The square root of 21988568 is about 4689.1969461732. The cubic root of 21988568 is about 280.1553899387.

The spelling of 21988568 in words is "twenty-one million, nine hundred eighty-eight thousand, five hundred sixty-eight".