81240579 has 24 divisors (see below), whose sum is σ = 136853600. Its totient is φ = 46421424.

The previous prime is 81240563. The next prime is 81240613. The reversal of 81240579 is 97504218.

81240579 is a `hidden beast` number, since 81 + 2 + 4 + 0 + 579 = 666.

It is not a de Polignac number, because 81240579 - 2⁴ = 81240563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81240539) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10072 + ... + 16245.

Almost surely, 2^81240579 is an apocalyptic number.

81240579 is a deficient number, since it is larger than the sum of its proper divisors (55613021).

81240579 is a wasteful number, since it uses less digits than its factorization.

81240579 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26344 (or 26327 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 81240579 is about 9013.3555904558. The cubic root of 81240579 is about 433.1028118416.

The spelling of 81240579 in words is "eighty-one million, two hundred forty thousand, five hundred seventy-nine".