81680408 has 16 divisors (see below), whose sum is σ = 153427560. Its totient is φ = 40766400.

The previous prime is 81680387. The next prime is 81680447. The reversal of 81680408 is 80408618.

It is a congruent number.

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, 4373 + ... + 13508.

Almost surely, 2^81680408 is an apocalyptic number.

It is an amenable number.

81680408 is a deficient number, since it is larger than the sum of its proper divisors (71747152).

81680408 is a wasteful number, since it uses less digits than its factorization.

81680408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18458 (or 18454 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 35.

The square root of 81680408 is about 9037.7213942453. The cubic root of 81680408 is about 433.8829984675.

The spelling of 81680408 in words is "eighty-one million, six hundred eighty thousand, four hundred eight".