81396240 has 40 divisors (see below), whose sum is σ = 252329088. Its totient is φ = 21705600.

The previous prime is 81396239. The next prime is 81396251. The reversal of 81396240 is 4269318.

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×81396240² = 13250695772275200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 169336 + ... + 169815.

Almost surely, 2^81396240 is an apocalyptic number.

81396240 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81396240 is an abundant number, since it is smaller than the sum of its proper divisors (170932848).

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

81396240 is a wasteful number, since it uses less digits than its factorization.

81396240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 339167 (or 339161 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 33.

The square root of 81396240 is about 9021.9864774893. The cubic root of 81396240 is about 433.3792508870.

The spelling of 81396240 in words is "eighty-one million, three hundred ninety-six thousand, two hundred forty".