81615337 has 2 divisors, whose sum is σ = 81615338. Its totient is φ = 81615336.

The previous prime is 81615323. The next prime is 81615341. The reversal of 81615337 is 73351618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 57517056 + 24098281 = 7584^2 + 4909^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81615337 is a prime.

It is a super-2 number, since 2×81615337² = 13322126467247138, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81615307) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40807668 + 40807669.

It is an arithmetic number, because the mean of its divisors is an integer number (40807669).

Almost surely, 2^81615337 is an apocalyptic number.

It is an amenable number.

81615337 is a deficient number, since it is larger than the sum of its proper divisors (1).

81615337 is an equidigital number, since it uses as much as digits as its factorization.

81615337 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15120, while the sum is 34.

The square root of 81615337 is about 9034.1207098422. The cubic root of 81615337 is about 433.7677496910.

The spelling of 81615337 in words is "eighty-one million, six hundred fifteen thousand, three hundred thirty-seven".