81515713 has 2 divisors, whose sum is σ = 81515714. Its totient is φ = 81515712.

The previous prime is 81515683. The next prime is 81515737. The reversal of 81515713 is 31751518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 67617729 + 13897984 = 8223^2 + 3728^2 .

It is a cyclic number.

It is not a de Polignac number, because 81515713 - 2¹³ = 81507521 is a prime.

It is a super-2 number, since 2×81515713² = 13289622931796738, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81515743) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40757856 + 40757857.

It is an arithmetic number, because the mean of its divisors is an integer number (40757857).

Almost surely, 2^81515713 is an apocalyptic number.

It is an amenable number.

81515713 is a deficient number, since it is larger than the sum of its proper divisors (1).

81515713 is an equidigital number, since it uses as much as digits as its factorization.

81515713 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4200, while the sum is 31.

The square root of 81515713 is about 9028.6052632729. The cubic root of 81515713 is about 433.5911845388.

It can be divided in two parts, 81515 and 713, that added together give a palindrome (82228).

The spelling of 81515713 in words is "eighty-one million, five hundred fifteen thousand, seven hundred thirteen".