71219821 has 2 divisors, whose sum is σ = 71219822. Its totient is φ = 71219820.

The previous prime is 71219807. The next prime is 71219831. The reversal of 71219821 is 12891217.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59074596 + 12145225 = 7686^2 + 3485^2 .

It is an emirp because it is prime and its reverse (12891217) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 71219821 - 2²⁵ = 37665389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71219801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35609910 + 35609911.

It is an arithmetic number, because the mean of its divisors is an integer number (35609911).

Almost surely, 2^71219821 is an apocalyptic number.

It is an amenable number.

71219821 is a deficient number, since it is larger than the sum of its proper divisors (1).

71219821 is an equidigital number, since it uses as much as digits as its factorization.

71219821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2016, while the sum is 31.

The square root of 71219821 is about 8439.1836690524. The cubic root of 71219821 is about 414.5086767842.

The spelling of 71219821 in words is "seventy-one million, two hundred nineteen thousand, eight hundred twenty-one".