71521531 has 4 divisors (see below), whose sum is σ = 72501352. Its totient is φ = 70541712.

The previous prime is 71521519. The next prime is 71521537. The reversal of 71521531 is 13512517.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71521531 is a prime.

It is a super-2 number, since 2×71521531² = 10230658793167922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 71521496 and 71521505.

It is not an unprimeable number, because it can be changed into a prime (71521537) 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, 489801 + ... + 489946.

It is an arithmetic number, because the mean of its divisors is an integer number (18125338).

Almost surely, 2^71521531 is an apocalyptic number.

71521531 is a deficient number, since it is larger than the sum of its proper divisors (979821).

71521531 is an equidigital number, since it uses as much as digits as its factorization.

71521531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 979820.

The product of its digits is 1050, while the sum is 25.

The square root of 71521531 is about 8457.0403215309. The cubic root of 71521531 is about 415.0931827335.

The spelling of 71521531 in words is "seventy-one million, five hundred twenty-one thousand, five hundred thirty-one".