215617901 has 2 divisors, whose sum is σ = 215617902. Its totient is φ = 215617900.

The previous prime is 215617873. The next prime is 215617903. The reversal of 215617901 is 109716512.

215617901 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., 186349801 + 29268100 = 13651^2 + 5410^2 .

It is a cyclic number.

It is not a de Polignac number, because 215617901 - 2¹⁸ = 215355757 is a prime.

It is a Sophie Germain prime.

Together with 215617903, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (215617903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107808950 + 107808951.

It is an arithmetic number, because the mean of its divisors is an integer number (107808951).

Almost surely, 2^215617901 is an apocalyptic number.

It is an amenable number.

215617901 is a deficient number, since it is larger than the sum of its proper divisors (1).

215617901 is an equidigital number, since it uses as much as digits as its factorization.

215617901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3780, while the sum is 32.

The square root of 215617901 is about 14683.9334307944. The cubic root of 215617901 is about 599.6459958058.

The spelling of 215617901 in words is "two hundred fifteen million, six hundred seventeen thousand, nine hundred one".