216991628 has 24 divisors (see below), whose sum is σ = 456825600. Its totient is φ = 88101648.

The previous prime is 216991583. The next prime is 216991633. The reversal of 216991628 is 826199612.

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, 203408 + ... + 204471.

It is an arithmetic number, because the mean of its divisors is an integer number (19034400).

Almost surely, 2^216991628 is an apocalyptic number.

216991628 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

216991628 is an abundant number, since it is smaller than the sum of its proper divisors (239833972).

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

216991628 is a wasteful number, since it uses less digits than its factorization.

216991628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407909 (or 407907 counting only the distinct ones).

The product of its digits is 93312, while the sum is 44.

The square root of 216991628 is about 14730.6356957193. The cubic root of 216991628 is about 600.9167725740.

The spelling of 216991628 in words is "two hundred sixteen million, nine hundred ninety-one thousand, six hundred twenty-eight".