81690900377 has 4 divisors (see below), whose sum is σ = 86496247476. Its totient is φ = 76885553280.

The previous prime is 81690900373. The next prime is 81690900397. The reversal of 81690900377 is 77300909618.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 76722906121 + 4967994256 = 276989^2 + 70484^2 .

It is a cyclic number.

It is not a de Polignac number, because 81690900377 - 2² = 81690900373 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81690900373) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2402673524 + ... + 2402673557.

It is an arithmetic number, because the mean of its divisors is an integer number (21624061869).

Almost surely, 2^81690900377 is an apocalyptic number.

It is an amenable number.

81690900377 is a deficient number, since it is larger than the sum of its proper divisors (4805347099).

81690900377 is a wasteful number, since it uses less digits than its factorization.

81690900377 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4805347098.

The product of its (nonzero) digits is 571536, while the sum is 50.

The spelling of 81690900377 in words is "eighty-one billion, six hundred ninety million, nine hundred thousand, three hundred seventy-seven".