81465940 has 24 divisors (see below), whose sum is σ = 172109952. Its totient is φ = 32389920.

The previous prime is 81465913. The next prime is 81465947. The reversal of 81465940 is 4956418.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 81465940.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81465947) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8856 + ... + 15535.

It is an arithmetic number, because the mean of its divisors is an integer number (7171248).

Almost surely, 2^81465940 is an apocalyptic number.

It is an amenable number.

81465940 is an abundant number, since it is smaller than the sum of its proper divisors (90644012).

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

81465940 is a wasteful number, since it uses less digits than its factorization.

81465940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24567 (or 24565 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 37.

The square root of 81465940 is about 9025.8484365737. The cubic root of 81465940 is about 433.5029171886.

The spelling of 81465940 in words is "eighty-one million, four hundred sixty-five thousand, nine hundred forty".