81751646 has 4 divisors (see below), whose sum is σ = 122627472. Its totient is φ = 40875822.

The previous prime is 81751613. The next prime is 81751687. The reversal of 81751646 is 64615718.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20437910 + ... + 20437913.

It is an arithmetic number, because the mean of its divisors is an integer number (30656868).

Almost surely, 2^81751646 is an apocalyptic number.

81751646 is a deficient number, since it is larger than the sum of its proper divisors (40875826).

81751646 is a wasteful number, since it uses less digits than its factorization.

81751646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40875825.

The product of its digits is 40320, while the sum is 38.

The square root of 81751646 is about 9041.6616835624. The cubic root of 81751646 is about 434.0090995990.

The spelling of 81751646 in words is "eighty-one million, seven hundred fifty-one thousand, six hundred forty-six".