165981278464 has 27 divisors (see below), whose sum is σ = 331327204663. Its totient is φ = 82987379968.

The previous prime is 165981278453. The next prime is 165981278471. The reversal of 165981278464 is 464872189561.

The square root of 165981278464 is 407408.

It is a perfect power (a square), and thus also a powerful number.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 6505797 + ... + 6531259.

Almost surely, 2^165981278464 is an apocalyptic number.

165981278464 is the 407408-th square number.

It is an amenable number.

165981278464 is a deficient number, since it is larger than the sum of its proper divisors (165345926199).

165981278464 is an frugal number, since it uses more digits than its factorization.

165981278464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50942 (or 25465 counting only the distinct ones).

The product of its digits is 23224320, while the sum is 61.

The spelling of 165981278464 in words is "one hundred sixty-five billion, nine hundred eighty-one million, two hundred seventy-eight thousand, four hundred sixty-four".