81692279 has 4 divisors (see below), whose sum is σ = 81849600. Its totient is φ = 81534960.

The previous prime is 81692231. The next prime is 81692291. The reversal of 81692279 is 97229618.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 97229618 = 2 ⋅48614809.

It is a cyclic number.

It is not a de Polignac number, because 81692279 - 2¹² = 81688183 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81692179) 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, 77879 + ... + 78920.

It is an arithmetic number, because the mean of its divisors is an integer number (20462400).

Almost surely, 2^81692279 is an apocalyptic number.

81692279 is a deficient number, since it is larger than the sum of its proper divisors (157321).

81692279 is a wasteful number, since it uses less digits than its factorization.

81692279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 157320.

The product of its digits is 108864, while the sum is 44.

The square root of 81692279 is about 9038.3781177820. The cubic root of 81692279 is about 433.9040168721.

The spelling of 81692279 in words is "eighty-one million, six hundred ninety-two thousand, two hundred seventy-nine".