81708786 has 12 divisors (see below), whose sum is σ = 177035742. Its totient is φ = 27236256.

The previous prime is 81708779. The next prime is 81708841. The reversal of 81708786 is 68780718.

It can be written as a sum of positive squares in only one way, i.e., 79762761 + 1946025 = 8931^2 + 1395^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 2269671 + ... + 2269706.

Almost surely, 2^81708786 is an apocalyptic number.

81708786 is an abundant number, since it is smaller than the sum of its proper divisors (95326956).

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

81708786 is a wasteful number, since it uses less digits than its factorization.

81708786 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4539385 (or 4539382 counting only the distinct ones).

The product of its (nonzero) digits is 150528, while the sum is 45.

The square root of 81708786 is about 9039.2912332771. The cubic root of 81708786 is about 433.9332402427.

The spelling of 81708786 in words is "eighty-one million, seven hundred eight thousand, seven hundred eighty-six".