81777492 has 48 divisors (see below), whose sum is σ = 213601920. Its totient is φ = 27055296.

The previous prime is 81777461. The next prime is 81777533. The reversal of 81777492 is 29477718.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12033 + ... + 17559.

It is an arithmetic number, because the mean of its divisors is an integer number (4450040).

Almost surely, 2^81777492 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 81777492, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (106800960).

81777492 is an abundant number, since it is smaller than the sum of its proper divisors (131824428).

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

81777492 is a wasteful number, since it uses less digits than its factorization.

81777492 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5677 (or 5669 counting only the distinct ones).

The product of its digits is 197568, while the sum is 45.

The square root of 81777492 is about 9043.0908432903. The cubic root of 81777492 is about 434.0548324896.

The spelling of 81777492 in words is "eighty-one million, seven hundred seventy-seven thousand, four hundred ninety-two".