81776440 has 16 divisors (see below), whose sum is σ = 183997080. Its totient is φ = 32710560.

The previous prime is 81776413. The next prime is 81776441. The reversal of 81776440 is 4467718.

It is a super-2 number, since 2×81776440² = 13374772278147200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81776440.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81776441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1022166 + ... + 1022245.

Almost surely, 2^81776440 is an apocalyptic number.

It is an amenable number.

81776440 is an abundant number, since it is smaller than the sum of its proper divisors (102220640).

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

81776440 is a wasteful number, since it uses less digits than its factorization.

81776440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2044422 (or 2044418 counting only the distinct ones).

The product of its (nonzero) digits is 37632, while the sum is 37.

The square root of 81776440 is about 9043.0326771499. The cubic root of 81776440 is about 434.0529712291.

The spelling of 81776440 in words is "eighty-one million, seven hundred seventy-six thousand, four hundred forty".