215643397 has 2 divisors, whose sum is σ = 215643398. Its totient is φ = 215643396.

The previous prime is 215643367. The next prime is 215643403. The reversal of 215643397 is 793346512.

It is a happy number.

215643397 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 147233956 + 68409441 = 12134^2 + 8271^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-215643397 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (215643367) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107821698 + 107821699.

It is an arithmetic number, because the mean of its divisors is an integer number (107821699).

Almost surely, 2^215643397 is an apocalyptic number.

It is an amenable number.

215643397 is a deficient number, since it is larger than the sum of its proper divisors (1).

215643397 is an equidigital number, since it uses as much as digits as its factorization.

215643397 is an evil number, because the sum of its binary digits is even.

The product of its digits is 136080, while the sum is 40.

The square root of 215643397 is about 14684.8015648833. The cubic root of 215643397 is about 599.6696301634.

The spelling of 215643397 in words is "two hundred fifteen million, six hundred forty-three thousand, three hundred ninety-seven".