21808977 has 16 divisors (see below), whose sum is σ = 31184640. Its totient is φ = 13508352.

The previous prime is 21808967. The next prime is 21808993. The reversal of 21808977 is 77980812.

It is not a de Polignac number, because 21808977 - 2¹¹ = 21806929 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21808967) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1323 + ... + 6735.

It is an arithmetic number, because the mean of its divisors is an integer number (1949040).

Almost surely, 2^21808977 is an apocalyptic number.

It is an amenable number.

21808977 is a deficient number, since it is larger than the sum of its proper divisors (9375663).

21808977 is a wasteful number, since it uses less digits than its factorization.

21808977 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5512.

The product of its (nonzero) digits is 56448, while the sum is 42.

The square root of 21808977 is about 4670.0082441041. The cubic root of 21808977 is about 279.3905835889.

The spelling of 21808977 in words is "twenty-one million, eight hundred eight thousand, nine hundred seventy-seven".