81879511 has 4 divisors (see below), whose sum is σ = 93576592. Its totient is φ = 70182432.

The previous prime is 81879487. The next prime is 81879521. The reversal of 81879511 is 11597818.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81879511 - 2¹¹ = 81877463 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 (81879521) 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, 5848530 + ... + 5848543.

It is an arithmetic number, because the mean of its divisors is an integer number (23394148).

Almost surely, 2^81879511 is an apocalyptic number.

81879511 is a deficient number, since it is larger than the sum of its proper divisors (11697081).

81879511 is a wasteful number, since it uses less digits than its factorization.

81879511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11697080.

The product of its digits is 20160, while the sum is 40.

The square root of 81879511 is about 9048.7298003642. The cubic root of 81879511 is about 434.2352547447.

The spelling of 81879511 in words is "eighty-one million, eight hundred seventy-nine thousand, five hundred eleven".