215645 has 16 divisors (see below), whose sum is σ = 285120. Its totient is φ = 155904.

The previous prime is 215617. The next prime is 215653. The reversal of 215645 is 546512.

It is a cyclic number.

It is not a de Polignac number, because 215645 - 2⁸ = 215389 is a prime.

It is an Ulam number.

215645 is a modest number, since divided by 645 gives 215 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 215645.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3626 + ... + 3684.

It is an arithmetic number, because the mean of its divisors is an integer number (17820).

2²¹⁵⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

215645 is a deficient number, since it is larger than the sum of its proper divisors (69475).

215645 is a wasteful number, since it uses less digits than its factorization.

215645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124.

The product of its digits is 1200, while the sum is 23.

The square root of 215645 is about 464.3759253019. The cubic root of 215645 is about 59.9671116055.

It can be divided in two parts, 2156 and 45, that multiplied together give a triangular number (97020 = T₄₄₀).

The spelling of 215645 in words is "two hundred fifteen thousand, six hundred forty-five".