81977906 has 8 divisors (see below), whose sum is σ = 124161024. Its totient is φ = 40590900.

The previous prime is 81977897. The next prime is 81977921. The reversal of 81977906 is 60977918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 198770 + ... + 199181.

It is an arithmetic number, because the mean of its divisors is an integer number (15520128).

Almost surely, 2^81977906 is an apocalyptic number.

81977906 is a deficient number, since it is larger than the sum of its proper divisors (42183118).

81977906 is a wasteful number, since it uses less digits than its factorization.

81977906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 398056.

The product of its (nonzero) digits is 190512, while the sum is 47.

The square root of 81977906 is about 9054.1651188831. The cubic root of 81977906 is about 434.4091259768.

The spelling of 81977906 in words is "eighty-one million, nine hundred seventy-seven thousand, nine hundred six".