81797870 has 64 divisors (see below), whose sum is σ = 188116992. Its totient is φ = 24864000.

The previous prime is 81797857. The next prime is 81797879. The reversal of 81797870 is 7879718.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81797879) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 30275 + ... + 32865.

It is an arithmetic number, because the mean of its divisors is an integer number (2939328).

Almost surely, 2^81797870 is an apocalyptic number.

81797870 is an abundant number, since it is smaller than the sum of its proper divisors (106319122).

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

81797870 is a wasteful number, since it uses less digits than its factorization.

81797870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2657.

The product of its (nonzero) digits is 197568, while the sum is 47.

The square root of 81797870 is about 9044.2174896450. The cubic root of 81797870 is about 434.0908833008.

The spelling of 81797870 in words is "eighty-one million, seven hundred ninety-seven thousand, eight hundred seventy".