81677579 has 4 divisors (see below), whose sum is σ = 82092384. Its totient is φ = 81262776.

The previous prime is 81677573. The next prime is 81677581. The reversal of 81677579 is 97577618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 97577618 = 2 ⋅48788809.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81677579 is a prime.

It is a super-2 number, since 2×81677579² = 13342453822602482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81677573) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 207107 + ... + 207500.

It is an arithmetic number, because the mean of its divisors is an integer number (20523096).

Almost surely, 2^81677579 is an apocalyptic number.

81677579 is a deficient number, since it is larger than the sum of its proper divisors (414805).

81677579 is a wasteful number, since it uses less digits than its factorization.

81677579 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 414804.

The product of its digits is 740880, while the sum is 50.

The square root of 81677579 is about 9037.5648822014. The cubic root of 81677579 is about 433.8779892321.

The spelling of 81677579 in words is "eighty-one million, six hundred seventy-seven thousand, five hundred seventy-nine".