1666842690 has 128 divisors (see below), whose sum is σ = 4348650240. Its totient is φ = 407347200.

The previous prime is 1666842677. The next prime is 1666842701. The reversal of 1666842690 is 962486661.

It is a happy number.

It is a super-2 number, since 2×1666842690² = 5556729106412872200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4075206 + ... + 4075614.

It is an arithmetic number, because the mean of its divisors is an integer number (33973830).

Almost surely, 2^1666842690 is an apocalyptic number.

1666842690 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1666842690, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2174325120).

1666842690 is an abundant number, since it is smaller than the sum of its proper divisors (2681807550).

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

1666842690 is a wasteful number, since it uses less digits than its factorization.

1666842690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 628.

The product of its (nonzero) digits is 746496, while the sum is 48.

The square root of 1666842690 is about 40826.9848262151. The cubic root of 1666842690 is about 1185.6728397751.

The spelling of 1666842690 in words is "one billion, six hundred sixty-six million, eight hundred forty-two thousand, six hundred ninety".