81429978 has 16 divisors (see below), whose sum is σ = 186125760. Its totient is φ = 23265696.

The previous prime is 81429973. The next prime is 81429979. The reversal of 81429978 is 87992418.

It is not an unprimeable number, because it can be changed into a prime (81429973) 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, 969363 + ... + 969446.

It is an arithmetic number, because the mean of its divisors is an integer number (11632860).

Almost surely, 2^81429978 is an apocalyptic number.

81429978 is an abundant number, since it is smaller than the sum of its proper divisors (104695782).

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

81429978 is a wasteful number, since it uses less digits than its factorization.

81429978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1938821.

The product of its digits is 290304, while the sum is 48.

The square root of 81429978 is about 9023.8560493838. The cubic root of 81429978 is about 433.4391198666.

The spelling of 81429978 in words is "eighty-one million, four hundred twenty-nine thousand, nine hundred seventy-eight".