71921221 has 2 divisors, whose sum is σ = 71921222. Its totient is φ = 71921220.

The previous prime is 71921183. The next prime is 71921231. The reversal of 71921221 is 12212917.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 67881121 + 4040100 = 8239^2 + 2010^2 .

It is an emirp because it is prime and its reverse (12212917) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71921221 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (71921231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 35960610 + 35960611.

It is an arithmetic number, because the mean of its divisors is an integer number (35960611).

Almost surely, 2^71921221 is an apocalyptic number.

It is an amenable number.

71921221 is a deficient number, since it is larger than the sum of its proper divisors (1).

71921221 is an equidigital number, since it uses as much as digits as its factorization.

71921221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 504, while the sum is 25.

The square root of 71921221 is about 8480.6380066596. The cubic root of 71921221 is about 415.8649806057.

The spelling of 71921221 in words is "seventy-one million, nine hundred twenty-one thousand, two hundred twenty-one".