81777730 has 8 divisors (see below), whose sum is σ = 147199932. Its totient is φ = 32711088.

The previous prime is 81777727. The next prime is 81777743. The reversal of 81777730 is 3777718.

It can be written as a sum of positive squares in 2 ways, for example, as 68608089 + 13169641 = 8283^2 + 3629^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4088877 + ... + 4088896.

Almost surely, 2^81777730 is an apocalyptic number.

81777730 is a deficient number, since it is larger than the sum of its proper divisors (65422202).

81777730 is a wasteful number, since it uses less digits than its factorization.

81777730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8177780.

The product of its (nonzero) digits is 57624, while the sum is 40.

The square root of 81777730 is about 9043.1040024983. The cubic root of 81777730 is about 434.0552535710.

The spelling of 81777730 in words is "eighty-one million, seven hundred seventy-seven thousand, seven hundred thirty".