81923745 has 16 divisors (see below), whose sum is σ = 131274432. Its totient is φ = 43627200.

The previous prime is 81923741. The next prime is 81923747. The reversal of 81923745 is 54732918.

It is not a de Polignac number, because 81923745 - 2² = 81923741 is a prime.

It is a super-2 number, since 2×81923745² = 13422999989650050, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81923741) by changing a digit.

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 in 15 ways as a sum of consecutive naturals, for example, 7270 + ... + 14720.

It is an arithmetic number, because the mean of its divisors is an integer number (8204652).

Almost surely, 2^81923745 is an apocalyptic number.

It is an amenable number.

81923745 is a deficient number, since it is larger than the sum of its proper divisors (49350687).

81923745 is a wasteful number, since it uses less digits than its factorization.

81923745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8192.

The product of its digits is 60480, while the sum is 39.

The square root of 81923745 is about 9051.1736807996. The cubic root of 81923745 is about 434.3134367145.

The spelling of 81923745 in words is "eighty-one million, nine hundred twenty-three thousand, seven hundred forty-five".