221631493373861 has 2 divisors, whose sum is σ = 221631493373862. Its totient is φ = 221631493373860.

The previous prime is 221631493373723. The next prime is 221631493373893. The reversal of 221631493373861 is 168373394136122.

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., 138551002851361 + 83080490522500 = 11770769^2 + 9114850^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221631493373861 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 221631493373861.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221631493873861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110815746686930 + 110815746686931.

It is an arithmetic number, because the mean of its divisors is an integer number (110815746686931).

Almost surely, 2^{221631493373861} is an apocalyptic number.

It is an amenable number.

221631493373861 is a deficient number, since it is larger than the sum of its proper divisors (1).

221631493373861 is an equidigital number, since it uses as much as digits as its factorization.

221631493373861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23514624, while the sum is 59.

The spelling of 221631493373861 in words is "two hundred twenty-one trillion, six hundred thirty-one billion, four hundred ninety-three million, three hundred seventy-three thousand, eight hundred sixty-one".