81319408 has 10 divisors (see below), whose sum is σ = 157556384. Its totient is φ = 40659696.

The previous prime is 81319397. The next prime is 81319409. The reversal of 81319408 is 80491318.

It is a happy number.

It is a super-2 number, since 2×81319408² = 13225692234940928, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81319409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2541216 + ... + 2541247.

Almost surely, 2^81319408 is an apocalyptic number.

It is an amenable number.

81319408 is a deficient number, since it is larger than the sum of its proper divisors (76236976).

81319408 is a wasteful number, since it uses less digits than its factorization.

81319408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5082471 (or 5082465 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 34.

The square root of 81319408 is about 9017.7274299016. The cubic root of 81319408 is about 433.2428486943.

The spelling of 81319408 in words is "eighty-one million, three hundred nineteen thousand, four hundred eight".