81499978 has 16 divisors (see below), whose sum is σ = 139941504. Its totient is φ = 34871760.

The previous prime is 81499973. The next prime is 81499981. The reversal of 81499978 is 87999418.

It is not an unprimeable number, because it can be changed into a prime (81499973) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4851 + ... + 13657.

It is an arithmetic number, because the mean of its divisors is an integer number (8746344).

Almost surely, 2^81499978 is an apocalyptic number.

81499978 is a deficient number, since it is larger than the sum of its proper divisors (58441526).

81499978 is a wasteful number, since it uses less digits than its factorization.

81499978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9477.

The product of its digits is 1306368, while the sum is 55.

The square root of 81499978 is about 9027.7338241665. The cubic root of 81499978 is about 433.5632840025.

The spelling of 81499978 in words is "eighty-one million, four hundred ninety-nine thousand, nine hundred seventy-eight".