81939480 has 64 divisors (see below), whose sum is σ = 280938240. Its totient is φ = 18728832.

The previous prime is 81939463. The next prime is 81939503. The reversal of 81939480 is 8493918.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

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, 47934 + ... + 49613.

It is an arithmetic number, because the mean of its divisors is an integer number (4389660).

Almost surely, 2^81939480 is an apocalyptic number.

It is an amenable number.

81939480 is an abundant number, since it is smaller than the sum of its proper divisors (198998760).

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

81939480 is a wasteful number, since it uses less digits than its factorization.

81939480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97568 (or 97564 counting only the distinct ones).

The product of its (nonzero) digits is 62208, while the sum is 42.

The square root of 81939480 is about 9052.0428633541. The cubic root of 81939480 is about 434.3412409628.

The spelling of 81939480 in words is "eighty-one million, nine hundred thirty-nine thousand, four hundred eighty".