221993731397 has 2 divisors, whose sum is σ = 221993731398. Its totient is φ = 221993731396.

The previous prime is 221993731361. The next prime is 221993731451. The reversal of 221993731397 is 793137399122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 150048544321 + 71945187076 = 387361^2 + 268226^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221993731397 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221993731997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110996865698 + 110996865699.

It is an arithmetic number, because the mean of its divisors is an integer number (110996865699).

Almost surely, 2^221993731397 is an apocalyptic number.

It is an amenable number.

221993731397 is a deficient number, since it is larger than the sum of its proper divisors (1).

221993731397 is an equidigital number, since it uses as much as digits as its factorization.

221993731397 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3857868, while the sum is 56.

The spelling of 221993731397 in words is "two hundred twenty-one billion, nine hundred ninety-three million, seven hundred thirty-one thousand, three hundred ninety-seven".