71513821 has 2 divisors, whose sum is σ = 71513822. Its totient is φ = 71513820.

The previous prime is 71513803. The next prime is 71513833. The reversal of 71513821 is 12831517.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 69305625 + 2208196 = 8325^2 + 1486^2 .

It is a cyclic number.

It is not a de Polignac number, because 71513821 - 2⁵ = 71513789 is a prime.

It is a super-2 number, since 2×71513821² = 10228453188040082, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 71513821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71513851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35756910 + 35756911.

It is an arithmetic number, because the mean of its divisors is an integer number (35756911).

Almost surely, 2^71513821 is an apocalyptic number.

It is an amenable number.

71513821 is a deficient number, since it is larger than the sum of its proper divisors (1).

71513821 is an equidigital number, since it uses as much as digits as its factorization.

71513821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1680, while the sum is 28.

The square root of 71513821 is about 8456.5844760163. The cubic root of 71513821 is about 415.0782665565.

The spelling of 71513821 in words is "seventy-one million, five hundred thirteen thousand, eight hundred twenty-one".