81616372 has 6 divisors (see below), whose sum is σ = 142828658. Its totient is φ = 40808184.

The previous prime is 81616361. The next prime is 81616373. The reversal of 81616372 is 27361618.

It can be written as a sum of positive squares in only one way, i.e., 55442916 + 26173456 = 7446^2 + 5116^2 .

It is a super-2 number, since 2×81616372² = 13322464356884768, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81616373) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10202043 + ... + 10202050.

Almost surely, 2^81616372 is an apocalyptic number.

It is an amenable number.

81616372 is a deficient number, since it is larger than the sum of its proper divisors (61212286).

81616372 is a wasteful number, since it uses less digits than its factorization.

81616372 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20404097 (or 20404095 counting only the distinct ones).

The product of its digits is 12096, while the sum is 34.

The square root of 81616372 is about 9034.1779924905. The cubic root of 81616372 is about 433.7695832831.

The spelling of 81616372 in words is "eighty-one million, six hundred sixteen thousand, three hundred seventy-two".