81639486 has 24 divisors (see below), whose sum is σ = 177080904. Its totient is φ = 27183120.

The previous prime is 81639431. The next prime is 81639511. The reversal of 81639486 is 68493618.

81639486 is a `hidden beast` number, since 8 + 1 + 639 + 4 + 8 + 6 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19456 + ... + 23276.

It is an arithmetic number, because the mean of its divisors is an integer number (7378371).

Almost surely, 2^81639486 is an apocalyptic number.

81639486 is an abundant number, since it is smaller than the sum of its proper divisors (95441418).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81639486 is a wasteful number, since it uses less digits than its factorization.

81639486 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5016 (or 5013 counting only the distinct ones).

The product of its digits is 248832, while the sum is 45.

The square root of 81639486 is about 9035.4571550088. The cubic root of 81639486 is about 433.8105276981.

The spelling of 81639486 in words is "eighty-one million, six hundred thirty-nine thousand, four hundred eighty-six".