81775637 has 4 divisors (see below), whose sum is σ = 83677440. Its totient is φ = 79873836.

The previous prime is 81775609. The next prime is 81775643. The reversal of 81775637 is 73657718.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81775637 - 2⁸ = 81775381 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81775657) 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, 950837 + ... + 950922.

It is an arithmetic number, because the mean of its divisors is an integer number (20919360).

Almost surely, 2^81775637 is an apocalyptic number.

It is an amenable number.

81775637 is a deficient number, since it is larger than the sum of its proper divisors (1901803).

81775637 is a wasteful number, since it uses less digits than its factorization.

81775637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1901802.

The product of its digits is 246960, while the sum is 44.

The square root of 81775637 is about 9042.9882782187. The cubic root of 81775637 is about 434.0515505034.

The spelling of 81775637 in words is "eighty-one million, seven hundred seventy-five thousand, six hundred thirty-seven".