21798816 has 48 divisors (see below), whose sum is σ = 61627104. Its totient is φ = 6706944.

The previous prime is 21798787. The next prime is 21798827. The reversal of 21798816 is 61889712.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors.

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, 7486 + ... + 9981.

It is an arithmetic number, because the mean of its divisors is an integer number (1283898).

Almost surely, 2^21798816 is an apocalyptic number.

21798816 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21798816 is the 2496-th nonagonal number.

It is an amenable number.

21798816 is an abundant number, since it is smaller than the sum of its proper divisors (39828288).

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

21798816 is a wasteful number, since it uses less digits than its factorization.

21798816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17493 (or 17485 counting only the distinct ones).

The product of its digits is 48384, while the sum is 42.

The square root of 21798816 is about 4668.9202177806. The cubic root of 21798816 is about 279.3471866470.

The spelling of 21798816 in words is "twenty-one million, seven hundred ninety-eight thousand, eight hundred sixteen".