72156961 has 4 divisors (see below), whose sum is σ = 73339924. Its totient is φ = 70974000.

The previous prime is 72156949. The next prime is 72156979. The reversal of 72156961 is 16965127.

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

It can be written as a sum of positive squares in 2 ways, for example, as 14776336 + 57380625 = 3844^2 + 7575^2 .

It is a cyclic number.

It is not a de Polignac number, because 72156961 - 2²¹ = 70059809 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 72156961.

It is not an unprimeable number, because it can be changed into a prime (72156991) 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, 591390 + ... + 591511.

It is an arithmetic number, because the mean of its divisors is an integer number (18334981).

Almost surely, 2^72156961 is an apocalyptic number.

It is an amenable number.

72156961 is a deficient number, since it is larger than the sum of its proper divisors (1182963).

72156961 is a wasteful number, since it uses less digits than its factorization.

72156961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1182962.

The product of its digits is 22680, while the sum is 37.

The square root of 72156961 is about 8494.5253546034. The cubic root of 72156961 is about 416.3188526395.

The spelling of 72156961 in words is "seventy-two million, one hundred fifty-six thousand, nine hundred sixty-one".