81372545 has 4 divisors (see below), whose sum is σ = 97647060. Its totient is φ = 65098032.

The previous prime is 81372539. The next prime is 81372547. The reversal of 81372545 is 54527318.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 43930384 + 37442161 = 6628^2 + 6119^2 .

It is a cyclic number.

It is not a de Polignac number, because 81372545 - 2⁶ = 81372481 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81372547) 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, 8137250 + ... + 8137259.

It is an arithmetic number, because the mean of its divisors is an integer number (24411765).

Almost surely, 2^81372545 is an apocalyptic number.

It is an amenable number.

81372545 is a deficient number, since it is larger than the sum of its proper divisors (16274515).

81372545 is a wasteful number, since it uses less digits than its factorization.

81372545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16274514.

The product of its digits is 33600, while the sum is 35.

The square root of 81372545 is about 9020.6732010421. The cubic root of 81372545 is about 433.3371935882.

The spelling of 81372545 in words is "eighty-one million, three hundred seventy-two thousand, five hundred forty-five".