81400388 has 12 divisors (see below), whose sum is σ = 142856700. Its totient is φ = 40584192.

The previous prime is 81400349. The next prime is 81400393. The reversal of 81400388 is 88300418.

It can be written as a sum of positive squares in 2 ways, for example, as 64770304 + 16630084 = 8048^2 + 4078^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27413 + ... + 30236.

It is an arithmetic number, because the mean of its divisors is an integer number (11904725).

Almost surely, 2^81400388 is an apocalyptic number.

It is an amenable number.

81400388 is a deficient number, since it is larger than the sum of its proper divisors (61456312).

81400388 is a wasteful number, since it uses less digits than its factorization.

81400388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 58006 (or 58004 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 32.

The square root of 81400388 is about 9022.2163574146. The cubic root of 81400388 is about 433.3866125154.

The spelling of 81400388 in words is "eighty-one million, four hundred thousand, three hundred eighty-eight".