71613581 has 6 divisors (see below), whose sum is σ = 77546250. Its totient is φ = 66104688.

The previous prime is 71613541. The next prime is 71613589. The reversal of 71613581 is 18531617.

It can be written as a sum of positive squares in 3 ways, for example, as 885481 + 70728100 = 941^2 + 8410^2 .

It is not a de Polignac number, because 71613581 - 2⁶ = 71613517 is a prime.

It is a super-2 number, since 2×71613581² = 10257009967287122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71613589) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 211706 + ... + 212043.

It is an arithmetic number, because the mean of its divisors is an integer number (12924375).

Almost surely, 2^71613581 is an apocalyptic number.

It is an amenable number.

71613581 is a deficient number, since it is larger than the sum of its proper divisors (5932669).

71613581 is a wasteful number, since it uses less digits than its factorization.

71613581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 423775 (or 423762 counting only the distinct ones).

The product of its digits is 5040, while the sum is 32.

The square root of 71613581 is about 8462.4807828438. The cubic root of 71613581 is about 415.2711848285.

It can be divided in two parts, 7161 and 3581, that multiplied together give a triangular number (25643541 = T₇₁₆₁).

The spelling of 71613581 in words is "seventy-one million, six hundred thirteen thousand, five hundred eighty-one".