217991464 has 16 divisors (see below), whose sum is σ = 412352820. Its totient is φ = 108030720.

The previous prime is 217991443. The next prime is 217991471. The reversal of 217991464 is 464199712.

217991464 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 175350564 + 42640900 = 13242^2 + 6530^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 217991464.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 119667 + ... + 121474.

Almost surely, 2^217991464 is an apocalyptic number.

It is an amenable number.

217991464 is a deficient number, since it is larger than the sum of its proper divisors (194361356).

217991464 is a wasteful number, since it uses less digits than its factorization.

217991464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 241260 (or 241256 counting only the distinct ones).

The product of its digits is 108864, while the sum is 43.

The square root of 217991464 is about 14764.5339919687. The cubic root of 217991464 is about 601.8383100893.

The spelling of 217991464 in words is "two hundred seventeen million, nine hundred ninety-one thousand, four hundred sixty-four".