72161081 has 4 divisors (see below), whose sum is σ = 72418164. Its totient is φ = 71904000.

The previous prime is 72161057. The next prime is 72161083. The reversal of 72161081 is 18016127.

72161081 = 39² + 40² + ... + 600².

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18016127 = 167 ⋅107881.

It can be written as a sum of positive squares in 2 ways, for example, as 29376400 + 42784681 = 5420^2 + 6541^2 .

It is a cyclic number.

It is not a de Polignac number, because 72161081 - 2²⁶ = 5052217 is a prime.

It is a super-2 number, since 2×72161081² = 10414443222177122, which contains 22 as substring.

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 72161081.

It is not an unprimeable number, because it can be changed into a prime (72161083) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 128120 + ... + 128681.

It is an arithmetic number, because the mean of its divisors is an integer number (18104541).

Almost surely, 2^72161081 is an apocalyptic number.

It is an amenable number.

72161081 is a deficient number, since it is larger than the sum of its proper divisors (257083).

72161081 is a wasteful number, since it uses less digits than its factorization.

72161081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 257082.

The product of its (nonzero) digits is 672, while the sum is 26.

The square root of 72161081 is about 8494.7678602773. The cubic root of 72161081 is about 416.3267761118.

The spelling of 72161081 in words is "seventy-two million, one hundred sixty-one thousand, eighty-one".