61221666 has 32 divisors (see below), whose sum is σ = 134120448. Its totient is φ = 18476240.

The previous prime is 61221649. The next prime is 61221701. The reversal of 61221666 is 66612216.

It is a nude number because it is divisible by every one of its digits.

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, 15595 + ... + 19121.

It is an arithmetic number, because the mean of its divisors is an integer number (4191264).

Almost surely, 2^61221666 is an apocalyptic number.

61221666 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

61221666 is an abundant number, since it is smaller than the sum of its proper divisors (72898782).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

61221666 is a wasteful number, since it uses less digits than its factorization.

61221666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3806.

The product of its digits is 5184, while the sum is 30.

The square root of 61221666 is about 7824.4275189946. The cubic root of 61221666 is about 394.1259657184.

The spelling of 61221666 in words is "sixty-one million, two hundred twenty-one thousand, six hundred sixty-six".