81357978 has 64 divisors (see below), whose sum is σ = 181665792. Its totient is φ = 24131520.

The previous prime is 81357961. The next prime is 81358001. The reversal of 81357978 is 87975318.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 425863 + ... + 426053.

It is an arithmetic number, because the mean of its divisors is an integer number (2838528).

Almost surely, 2^81357978 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81357978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (90832896).

81357978 is an abundant number, since it is smaller than the sum of its proper divisors (100307814).

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

81357978 is a wasteful number, since it uses less digits than its factorization.

81357978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 379.

The product of its digits is 423360, while the sum is 48.

The square root of 81357978 is about 9019.8657417946. The cubic root of 81357978 is about 433.3113339259.

The spelling of 81357978 in words is "eighty-one million, three hundred fifty-seven thousand, nine hundred seventy-eight".