1620221666 has 16 divisors (see below), whose sum is σ = 2780090304. Its totient is φ = 693738864.

The previous prime is 1620221623. The next prime is 1620221693. The reversal of 1620221666 is 6661220261.

It is a Curzon 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, 37640 + ... + 68243.

It is an arithmetic number, because the mean of its divisors is an integer number (173755644).

Almost surely, 2^1620221666 is an apocalyptic number.

1620221666 is a deficient number, since it is larger than the sum of its proper divisors (1159868638).

1620221666 is a wasteful number, since it uses less digits than its factorization.

1620221666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106985.

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 1620221666 is about 40251.9771688299. The cubic root of 1620221666 is about 1174.5138573799.

The spelling of 1620221666 in words is "one billion, six hundred twenty million, two hundred twenty-one thousand, six hundred sixty-six".