661166215 has 8 divisors (see below), whose sum is σ = 820758240. Its totient is φ = 510693792.

The previous prime is 661166201. The next prime is 661166221. The reversal of 661166215 is 512661166.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 661166215 - 2¹⁷ = 661035143 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2279739 + ... + 2280028.

It is an arithmetic number, because the mean of its divisors is an integer number (102594780).

Almost surely, 2^661166215 is an apocalyptic number.

661166215 is a deficient number, since it is larger than the sum of its proper divisors (159592025).

661166215 is a wasteful number, since it uses less digits than its factorization.

661166215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4559801.

The product of its digits is 12960, while the sum is 34.

The square root of 661166215 is about 25713.1525682869. The cubic root of 661166215 is about 871.1712831827.

The spelling of 661166215 in words is "six hundred sixty-one million, one hundred sixty-six thousand, two hundred fifteen".