216515951 has 4 divisors (see below), whose sum is σ = 225929712. Its totient is φ = 207102192.

The previous prime is 216515947. The next prime is 216515953. The reversal of 216515951 is 159515612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 216515951 - 2² = 216515947 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216515953) 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, 4706846 + ... + 4706891.

It is an arithmetic number, because the mean of its divisors is an integer number (56482428).

Almost surely, 2^216515951 is an apocalyptic number.

216515951 is a deficient number, since it is larger than the sum of its proper divisors (9413761).

216515951 is an equidigital number, since it uses as much as digits as its factorization.

216515951 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9413760.

The product of its digits is 13500, while the sum is 35.

The square root of 216515951 is about 14714.4809966237. The cubic root of 216515951 is about 600.4773525310.

The spelling of 216515951 in words is "two hundred sixteen million, five hundred fifteen thousand, nine hundred fifty-one".