81772147 has 4 divisors (see below), whose sum is σ = 83112736. Its totient is φ = 80431560.

The previous prime is 81772129. The next prime is 81772157. The reversal of 81772147 is 74127718.

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

It is a cyclic number.

It is not a de Polignac number, because 81772147 - 2¹⁵ = 81739379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81772157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 670203 + ... + 670324.

It is an arithmetic number, because the mean of its divisors is an integer number (20778184).

Almost surely, 2^81772147 is an apocalyptic number.

81772147 is a deficient number, since it is larger than the sum of its proper divisors (1340589).

81772147 is a wasteful number, since it uses less digits than its factorization.

81772147 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1340588.

The product of its digits is 21952, while the sum is 37.

The square root of 81772147 is about 9042.7953089739. The cubic root of 81772147 is about 434.0453756347.

The spelling of 81772147 in words is "eighty-one million, seven hundred seventy-two thousand, one hundred forty-seven".