215551317 has 4 divisors (see below), whose sum is σ = 287401760. Its totient is φ = 143700876.

The previous prime is 215551291. The next prime is 215551321. The reversal of 215551317 is 713155512.

215551317 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 215551317 - 2¹⁴ = 215534933 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215551327) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35925217 + ... + 35925222.

It is an arithmetic number, because the mean of its divisors is an integer number (71850440).

Almost surely, 2^215551317 is an apocalyptic number.

It is an amenable number.

215551317 is a deficient number, since it is larger than the sum of its proper divisors (71850443).

215551317 is an equidigital number, since it uses as much as digits as its factorization.

215551317 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71850442.

The product of its digits is 5250, while the sum is 30.

The square root of 215551317 is about 14681.6660158171. Note that the first 3 decimals coincide. The cubic root of 215551317 is about 599.5842647847.

The spelling of 215551317 in words is "two hundred fifteen million, five hundred fifty-one thousand, three hundred seventeen".