71518921 has 2 divisors, whose sum is σ = 71518922. Its totient is φ = 71518920.

The previous prime is 71518873. The next prime is 71518927. The reversal of 71518921 is 12981517.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70896400 + 622521 = 8420^2 + 789^2 .

It is a cyclic number.

It is not a de Polignac number, because 71518921 - 2¹¹ = 71516873 is a prime.

It is a super-2 number, since 2×71518921² = 10229912122008482, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (71518927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35759460 + 35759461.

It is an arithmetic number, because the mean of its divisors is an integer number (35759461).

Almost surely, 2^71518921 is an apocalyptic number.

It is an amenable number.

71518921 is a deficient number, since it is larger than the sum of its proper divisors (1).

71518921 is an equidigital number, since it uses as much as digits as its factorization.

71518921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5040, while the sum is 34.

The square root of 71518921 is about 8456.8860108198. The cubic root of 71518921 is about 415.0881334084.

The spelling of 71518921 in words is "seventy-one million, five hundred eighteen thousand, nine hundred twenty-one".