81579960 has 384 divisors, whose sum is σ = 345945600. Its totient is φ = 16796160.

The previous prime is 81579947. The next prime is 81579973. The reversal of 81579960 is 6997518.

It is an interprime number because it is at equal distance from previous prime (81579947) and next prime (81579973).

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 748386 + ... + 748494.

It is an arithmetic number, because the mean of its divisors is an integer number (900900).

Almost surely, 2^81579960 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81579960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (172972800).

81579960 is an abundant number, since it is smaller than the sum of its proper divisors (264365640).

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

81579960 is a wasteful number, since it uses less digits than its factorization.

81579960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153 (or 137 counting only the distinct ones).

The product of its (nonzero) digits is 136080, while the sum is 45.

The square root of 81579960 is about 9032.1625317528. The cubic root of 81579960 is about 433.7050669486.

The spelling of 81579960 in words is "eighty-one million, five hundred seventy-nine thousand, nine hundred sixty".