81261792 has 120 divisors (see below), whose sum is σ = 242045496. Its totient is φ = 26742528.

The previous prime is 81261767. The next prime is 81261793. The reversal of 81261792 is 29716218.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81261793) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 277198 + ... + 277490.

Almost surely, 2^81261792 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 81261792, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121022748).

81261792 is an abundant number, since it is smaller than the sum of its proper divisors (160783704).

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

81261792 is a wasteful number, since it uses less digits than its factorization.

81261792 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 422 (or 405 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 81261792 is about 9014.5322674002. The cubic root of 81261792 is about 433.1405048703.

The spelling of 81261792 in words is "eighty-one million, two hundred sixty-one thousand, seven hundred ninety-two".