216656451 has 20 divisors (see below), whose sum is σ = 353071224. Its totient is φ = 131306400.

The previous prime is 216656443. The next prime is 216656459. The reversal of 216656451 is 154656612.

216656451 is a `hidden beast` number, since 2 + 1 + 6 + 6 + 5 + 645 + 1 = 666.

It is an interprime number because it is at equal distance from previous prime (216656443) and next prime (216656459).

It is not a de Polignac number, because 216656451 - 2³ = 216656443 is a prime.

It is not an unprimeable number, because it can be changed into a prime (216656459) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 120690 + ... + 122471.

Almost surely, 2^216656451 is an apocalyptic number.

216656451 is a deficient number, since it is larger than the sum of its proper divisors (136414773).

216656451 is a wasteful number, since it uses less digits than its factorization.

216656451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 243184 (or 243175 counting only the distinct ones).

The product of its digits is 43200, while the sum is 36.

The square root of 216656451 is about 14719.2544308467. The cubic root of 216656451 is about 600.6072102855.

The spelling of 216656451 in words is "two hundred sixteen million, six hundred fifty-six thousand, four hundred fifty-one".