81377766 has 24 divisors (see below), whose sum is σ = 176487480. Its totient is φ = 27099936.

The previous prime is 81377753. The next prime is 81377767. The reversal of 81377766 is 66777318.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81377767) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 30265 + ... + 32843.

It is an arithmetic number, because the mean of its divisors is an integer number (7353645).

Almost surely, 2^81377766 is an apocalyptic number.

81377766 is an abundant number, since it is smaller than the sum of its proper divisors (95109714).

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

81377766 is a wasteful number, since it uses less digits than its factorization.

81377766 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4340 (or 4337 counting only the distinct ones).

The product of its digits is 296352, while the sum is 45.

The square root of 81377766 is about 9020.9625872187. The cubic root of 81377766 is about 433.3464612722.

The spelling of 81377766 in words is "eighty-one million, three hundred seventy-seven thousand, seven hundred sixty-six".