216921478638 has 16 divisors (see below), whose sum is σ = 433979124480. Its totient is φ = 72284465016.

The previous prime is 216921478589. The next prime is 216921478661. The reversal of 216921478638 is 836874129612.

It is a happy number.

It is a congruent number.

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, 5652918 + ... + 5691161.

It is an arithmetic number, because the mean of its divisors is an integer number (27123695280).

Almost surely, 2^216921478638 is an apocalyptic number.

216921478638 is an abundant number, since it is smaller than the sum of its proper divisors (217057645842).

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

216921478638 is a wasteful number, since it uses less digits than its factorization.

216921478638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11347271.

The product of its digits is 6967296, while the sum is 57.

The spelling of 216921478638 in words is "two hundred sixteen billion, nine hundred twenty-one million, four hundred seventy-eight thousand, six hundred thirty-eight".