81651418 has 16 divisors (see below), whose sum is σ = 125737920. Its totient is φ = 39743200.

The previous prime is 81651413. The next prime is 81651421. The reversal of 81651418 is 81415618.

It is a happy number.

It is a super-2 number, since 2×81651418² = 13333908122821448, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81651413) 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 7 ways as a sum of consecutive naturals, for example, 53283 + ... + 54793.

It is an arithmetic number, because the mean of its divisors is an integer number (7858620).

Almost surely, 2^81651418 is an apocalyptic number.

81651418 is a deficient number, since it is larger than the sum of its proper divisors (44086502).

81651418 is a wasteful number, since it uses less digits than its factorization.

81651418 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2213.

The product of its digits is 7680, while the sum is 34.

The square root of 81651418 is about 9036.1174184491. The cubic root of 81651418 is about 433.8316611607.

The spelling of 81651418 in words is "eighty-one million, six hundred fifty-one thousand, four hundred eighteen".