81399070 has 32 divisors (see below), whose sum is σ = 153404928. Its totient is φ = 31039008.

The previous prime is 81399067. The next prime is 81399083. The reversal of 81399070 is 7099318.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 125487 + ... + 126133.

It is an arithmetic number, because the mean of its divisors is an integer number (4793904).

Almost surely, 2^81399070 is an apocalyptic number.

81399070 is a deficient number, since it is larger than the sum of its proper divisors (72005858).

81399070 is a wasteful number, since it uses less digits than its factorization.

81399070 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1224.

The product of its (nonzero) digits is 13608, while the sum is 37.

The square root of 81399070 is about 9022.1433151996. The cubic root of 81399070 is about 433.3842734330.

The spelling of 81399070 in words is "eighty-one million, three hundred ninety-nine thousand, seventy".