646220666 has 32 divisors (see below), whose sum is σ = 1255820160. Its totient is φ = 242191296.

The previous prime is 646220623. The next prime is 646220737. The reversal of 646220666 is 666022646.

It is a super-2 number, since 2×646220666² = 835202298330967112, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (38).

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, 89981 + ... + 96896.

It is an arithmetic number, because the mean of its divisors is an integer number (39244380).

Almost surely, 2^646220666 is an apocalyptic number.

646220666 is a deficient number, since it is larger than the sum of its proper divisors (609599494).

646220666 is a wasteful number, since it uses less digits than its factorization.

646220666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186918.

The product of its (nonzero) digits is 124416, while the sum is 38.

The square root of 646220666 is about 25420.8706774571. The cubic root of 646220666 is about 864.5569655927.

The spelling of 646220666 in words is "six hundred forty-six million, two hundred twenty thousand, six hundred sixty-six".