81401745 has 16 divisors (see below), whose sum is σ = 131440320. Its totient is φ = 43015104.

The previous prime is 81401741. The next prime is 81401759. The reversal of 81401745 is 54710418.

81401745 = 81² + 82² + ... + 625².

It is not a de Polignac number, because 81401745 - 2² = 81401741 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81401741) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23259 + ... + 26528.

It is an arithmetic number, because the mean of its divisors is an integer number (8215020).

Almost surely, 2^81401745 is an apocalyptic number.

It is an amenable number.

81401745 is a deficient number, since it is larger than the sum of its proper divisors (50038575).

81401745 is a wasteful number, since it uses less digits than its factorization.

81401745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49904.

The product of its (nonzero) digits is 4480, while the sum is 30.

The square root of 81401745 is about 9022.2915603521. The cubic root of 81401745 is about 433.3890207855.

The spelling of 81401745 in words is "eighty-one million, four hundred one thousand, seven hundred forty-five".