81977905 has 16 divisors (see below), whose sum is σ = 101018880. Its totient is φ = 63842688.

The previous prime is 81977897. The next prime is 81977921. The reversal of 81977905 is 50977918.

It is a cyclic number.

It is not a de Polignac number, because 81977905 - 2³ = 81977897 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27414 + ... + 30256.

It is an arithmetic number, because the mean of its divisors is an integer number (6313680).

Almost surely, 2^81977905 is an apocalyptic number.

It is an amenable number.

81977905 is a deficient number, since it is larger than the sum of its proper divisors (19040975).

81977905 is a wasteful number, since it uses less digits than its factorization.

81977905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3000.

The product of its (nonzero) digits is 158760, while the sum is 46.

The square root of 81977905 is about 9054.1650636599. The cubic root of 81977905 is about 434.4091242104.

The spelling of 81977905 in words is "eighty-one million, nine hundred seventy-seven thousand, nine hundred five".