215901 has 24 divisors (see below), whose sum is σ = 374400. Its totient is φ = 117216.

The previous prime is 215899. The next prime is 215909. The reversal of 215901 is 109512.

It is not a de Polignac number, because 215901 - 2¹ = 215899 is a prime.

It is a super-2 number, since 2×215901² = 93226483602, which contains 22 as substring.

It is a Curzon number.

215901 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1375 + ... + 1523.

It is an arithmetic number, because the mean of its divisors is an integer number (15600).

2²¹⁵⁹⁰¹ is an apocalyptic number.

215901 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

215901 is a deficient number, since it is larger than the sum of its proper divisors (158499).

215901 is a wasteful number, since it uses less digits than its factorization.

215901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 185 (or 182 counting only the distinct ones).

The product of its (nonzero) digits is 90, while the sum is 18.

The square root of 215901 is about 464.6514822961. The cubic root of 215901 is about 59.9908319325.

The spelling of 215901 in words is "two hundred fifteen thousand, nine hundred one".