221957391197 has 2 divisors, whose sum is σ = 221957391198. Its totient is φ = 221957391196.

The previous prime is 221957391151. The next prime is 221957391209. The reversal of 221957391197 is 791193759122.

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., 116735655556 + 105221735641 = 341666^2 + 324379^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221957391197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221957391497) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110978695598 + 110978695599.

It is an arithmetic number, because the mean of its divisors is an integer number (110978695599).

Almost surely, 2^221957391197 is an apocalyptic number.

It is an amenable number.

221957391197 is a deficient number, since it is larger than the sum of its proper divisors (1).

221957391197 is an equidigital number, since it uses as much as digits as its factorization.

221957391197 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2143260, while the sum is 56.

The spelling of 221957391197 in words is "two hundred twenty-one billion, nine hundred fifty-seven million, three hundred ninety-one thousand, one hundred ninety-seven".