81949760 has 28 divisors (see below), whose sum is σ = 195143628. Its totient is φ = 32779776.

The previous prime is 81949733. The next prime is 81949799. The reversal of 81949760 is 6794918.

It can be written as a sum of positive squares in 2 ways, for example, as 10445824 + 71503936 = 3232^2 + 8456^2 .

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, 127727 + ... + 128366.

Almost surely, 2^81949760 is an apocalyptic number.

81949760 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81949760 is an abundant number, since it is smaller than the sum of its proper divisors (113193868).

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

81949760 is a wasteful number, since it uses less digits than its factorization.

81949760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256110 (or 256100 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 44.

The square root of 81949760 is about 9052.6106731705. The cubic root of 81949760 is about 434.3594041292.

The spelling of 81949760 in words is "eighty-one million, nine hundred forty-nine thousand, seven hundred sixty".