81257499 has 12 divisors (see below), whose sum is σ = 121719416. Its totient is φ = 54171504.

The previous prime is 81257483. The next prime is 81257503. The reversal of 81257499 is 99475218.

It is not a de Polignac number, because 81257499 - 2⁴ = 81257483 is a prime.

It is a super-2 number, since 2×81257499² = 13205562287470002, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81257599) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 166954 + ... + 167439.

Almost surely, 2^81257499 is an apocalyptic number.

81257499 is a deficient number, since it is larger than the sum of its proper divisors (40461917).

81257499 is an equidigital number, since it uses as much as digits as its factorization.

81257499 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334408 (or 334396 counting only the distinct ones).

The product of its digits is 181440, while the sum is 45.

The square root of 81257499 is about 9014.2941487395. The cubic root of 81257499 is about 433.1328772391.

It can be divided in two parts, 812 and 57499, that added together give a triangular number (58311 = T₃₄₁).

The spelling of 81257499 in words is "eighty-one million, two hundred fifty-seven thousand, four hundred ninety-nine".