216984961 has 4 divisors (see below), whose sum is σ = 218693632. Its totient is φ = 215276292.

The previous prime is 216984919. The next prime is 216985001. The reversal of 216984961 is 169489612.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 216984961 - 2¹⁵ = 216952193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216985961) 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, 854145 + ... + 854398.

It is an arithmetic number, because the mean of its divisors is an integer number (54673408).

Almost surely, 2^216984961 is an apocalyptic number.

It is an amenable number.

216984961 is a deficient number, since it is larger than the sum of its proper divisors (1708671).

216984961 is a wasteful number, since it uses less digits than its factorization.

216984961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1708670.

The product of its digits is 186624, while the sum is 46.

The square root of 216984961 is about 14730.4093968905. The cubic root of 216984961 is about 600.9106181843.

The spelling of 216984961 in words is "two hundred sixteen million, nine hundred eighty-four thousand, nine hundred sixty-one".