71772181 has 24 divisors (see below), whose sum is σ = 84788424. Its totient is φ = 60149760.

The previous prime is 71772157. The next prime is 71772191. The reversal of 71772181 is 18127717.

71772181 = 5990² + 5991².

It can be written as a sum of positive squares in 12 ways, for example, as 54257956 + 17514225 = 7366^2 + 4185^2 .

It is not a de Polignac number, because 71772181 - 2²⁵ = 38217749 is a prime.

It is a super-2 number, since 2×71772181² = 10302491930993522, which contains 22 as substring.

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71772191) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 806385 + ... + 806473.

It is an arithmetic number, because the mean of its divisors is an integer number (3532851).

Almost surely, 2^71772181 is an apocalyptic number.

71772181 is the 5991-st centered square number.

It is an amenable number.

71772181 is a deficient number, since it is larger than the sum of its proper divisors (13016243).

71772181 is a wasteful number, since it uses less digits than its factorization.

71772181 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249 (or 160 counting only the distinct ones).

The product of its digits is 5488, while the sum is 34.

The square root of 71772181 is about 8471.8463749055. The cubic root of 71772181 is about 415.5775208055.

Adding to 71772181 its reverse (18127717), we get a palindrome (89899898).

The spelling of 71772181 in words is "seventy-one million, seven hundred seventy-two thousand, one hundred eighty-one".