215964661 has 4 divisors (see below), whose sum is σ = 235597824. Its totient is φ = 196331500.

The previous prime is 215964611. The next prime is 215964673. The reversal of 215964661 is 166469512.

It is a happy number.

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 a cyclic number.

It is not a de Polignac number, because 215964661 - 2¹³ = 215956469 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (215964611) 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, 9816565 + ... + 9816586.

It is an arithmetic number, because the mean of its divisors is an integer number (58899456).

Almost surely, 2^215964661 is an apocalyptic number.

It is an amenable number.

215964661 is a deficient number, since it is larger than the sum of its proper divisors (19633163).

215964661 is a wasteful number, since it uses less digits than its factorization.

215964661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19633162.

The product of its digits is 77760, while the sum is 40.

The square root of 215964661 is about 14695.7361503261. The cubic root of 215964661 is about 599.9672769191.

The spelling of 215964661 in words is "two hundred fifteen million, nine hundred sixty-four thousand, six hundred sixty-one".