81951746 has 4 divisors (see below), whose sum is σ = 122927622. Its totient is φ = 40975872.

The previous prime is 81951733. The next prime is 81951757. The reversal of 81951746 is 64715918.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 64715918 = 2 ⋅32357959.

It can be written as a sum of positive squares in only one way, i.e., 69973225 + 11978521 = 8365^2 + 3461^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20487935 + ... + 20487938.

Almost surely, 2^81951746 is an apocalyptic number.

81951746 is a deficient number, since it is larger than the sum of its proper divisors (40975876).

81951746 is a wasteful number, since it uses less digits than its factorization.

81951746 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40975875.

The product of its digits is 60480, while the sum is 41.

The square root of 81951746 is about 9052.7203646197. The cubic root of 81951746 is about 434.3629129083.

The spelling of 81951746 in words is "eighty-one million, nine hundred fifty-one thousand, seven hundred forty-six".