215123661 has 64 divisors (see below), whose sum is σ = 354585600. Its totient is φ = 128314368.

The previous prime is 215123659. The next prime is 215123677. The reversal of 215123661 is 166321512.

215123661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 215123661 - 2¹ = 215123659 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215123611) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 899980 + ... + 900218.

It is an arithmetic number, because the mean of its divisors is an integer number (5540400).

Almost surely, 2^215123661 is an apocalyptic number.

It is an amenable number.

215123661 is a deficient number, since it is larger than the sum of its proper divisors (139461939).

215123661 is a wasteful number, since it uses less digits than its factorization.

215123661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 355 (or 349 counting only the distinct ones).

The product of its digits is 2160, while the sum is 27.

The square root of 215123661 is about 14667.0944975479. The cubic root of 215123661 is about 599.1874751690.

The spelling of 215123661 in words is "two hundred fifteen million, one hundred twenty-three thousand, six hundred sixty-one".