71631221 has 4 divisors (see below), whose sum is σ = 71648844. Its totient is φ = 71613600.

The previous prime is 71631211. The next prime is 71631227. The reversal of 71631221 is 12213617.

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 50608996 + 21022225 = 7114^2 + 4585^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71631221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71631227) 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, 731 + ... + 11991.

It is an arithmetic number, because the mean of its divisors is an integer number (17912211).

Almost surely, 2^71631221 is an apocalyptic number.

It is an amenable number.

71631221 is a deficient number, since it is larger than the sum of its proper divisors (17623).

71631221 is a wasteful number, since it uses less digits than its factorization.

71631221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17622.

The product of its digits is 504, while the sum is 23.

The square root of 71631221 is about 8463.5229662358. The cubic root of 71631221 is about 415.3052788379.

Adding to 71631221 its reverse (12213617), we get a palindrome (83844838).

The spelling of 71631221 in words is "seventy-one million, six hundred thirty-one thousand, two hundred twenty-one".