21878616 has 32 divisors (see below), whose sum is σ = 55627200. Its totient is φ = 7168800.

The previous prime is 21878573. The next prime is 21878621. The reversal of 21878616 is 61687812.

It is a Smith number, since the sum of its digits (39) 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, 6310 + ... + 9141.

It is an arithmetic number, because the mean of its divisors is an integer number (1738350).

Almost surely, 2^21878616 is an apocalyptic number.

It is an amenable number.

21878616 is an abundant number, since it is smaller than the sum of its proper divisors (33748584).

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

21878616 is a wasteful number, since it uses less digits than its factorization.

21878616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15519 (or 15515 counting only the distinct ones).

The product of its digits is 32256, while the sum is 39.

The square root of 21878616 is about 4677.4582841539. The cubic root of 21878616 is about 279.6876448778.

The spelling of 21878616 in words is "twenty-one million, eight hundred seventy-eight thousand, six hundred sixteen".