81672640 has 168 divisors, whose sum is σ = 236902752. Its totient is φ = 26265600.

The previous prime is 81672623. The next prime is 81672667. The reversal of 81672640 is 4627618.

It is a junction number, because it is equal to n+sod(n) for n = 81672596 and 81672605.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 808590 + ... + 808690.

Almost surely, 2^81672640 is an apocalyptic number.

81672640 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81672640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118451376).

81672640 is an abundant number, since it is smaller than the sum of its proper divisors (155230112).

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

81672640 is a wasteful number, since it uses less digits than its factorization.

81672640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 163 (or 134 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 34.

The square root of 81672640 is about 9037.2916296864. The cubic root of 81672640 is about 433.8692435984.

The spelling of 81672640 in words is "eighty-one million, six hundred seventy-two thousand, six hundred forty".