81538877 has 4 divisors (see below), whose sum is σ = 93187296. Its totient is φ = 69890460.

The previous prime is 81538837. The next prime is 81538889. The reversal of 81538877 is 77883518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81538877 - 2¹⁰ = 81537853 is a prime.

It is a super-2 number, since 2×81538877² = 13297176924842258, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81538837) 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, 5824199 + ... + 5824212.

It is an arithmetic number, because the mean of its divisors is an integer number (23296824).

Almost surely, 2^81538877 is an apocalyptic number.

It is an amenable number.

81538877 is a deficient number, since it is larger than the sum of its proper divisors (11648419).

81538877 is a wasteful number, since it uses less digits than its factorization.

81538877 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11648418.

The product of its digits is 376320, while the sum is 47.

The square root of 81538877 is about 9029.8879838013. The cubic root of 81538877 is about 433.6322512837.

The spelling of 81538877 in words is "eighty-one million, five hundred thirty-eight thousand, eight hundred seventy-seven".