71405821 has 2 divisors, whose sum is σ = 71405822. Its totient is φ = 71405820.

The previous prime is 71405783. The next prime is 71405827. The reversal of 71405821 is 12850417.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 66504025 + 4901796 = 8155^2 + 2214^2 .

It is an emirp because it is prime and its reverse (12850417) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 71405821 - 2⁹ = 71405309 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 71405821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71405827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35702910 + 35702911.

It is an arithmetic number, because the mean of its divisors is an integer number (35702911).

Almost surely, 2^71405821 is an apocalyptic number.

It is an amenable number.

71405821 is a deficient number, since it is larger than the sum of its proper divisors (1).

71405821 is an equidigital number, since it uses as much as digits as its factorization.

71405821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 71405821 is about 8450.1965065908. The cubic root of 71405821 is about 414.8692112172.

The spelling of 71405821 in words is "seventy-one million, four hundred five thousand, eight hundred twenty-one".