216557920 has 24 divisors (see below), whose sum is σ = 511618464. Its totient is φ = 86623104.

The previous prime is 216557893. The next prime is 216557921. The reversal of 216557920 is 29755612.

It is a self number, because there is not a number n which added to its sum of digits gives 216557920.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216557921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 676584 + ... + 676903.

It is an arithmetic number, because the mean of its divisors is an integer number (21317436).

Almost surely, 2^216557920 is an apocalyptic number.

216557920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

216557920 is an abundant number, since it is smaller than the sum of its proper divisors (295060544).

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

216557920 is a wasteful number, since it uses less digits than its factorization.

216557920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1353502 (or 1353494 counting only the distinct ones).

The product of its (nonzero) digits is 37800, while the sum is 37.

The square root of 216557920 is about 14715.9070396629. The cubic root of 216557920 is about 600.5161484499.

The spelling of 216557920 in words is "two hundred sixteen million, five hundred fifty-seven thousand, nine hundred twenty".