1666271880 has 384 divisors, whose sum is σ = 7018502400. Its totient is φ = 332937216.

The previous prime is 1666271809. The next prime is 1666271903. The reversal of 1666271880 is 881726661.

1666271880 = T₄₃₁ + T₄₃₂ + ... + T₂₁₅₉.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 621102 + ... + 623778.

It is an arithmetic number, because the mean of its divisors is an integer number (18277350).

Almost surely, 2^1666271880 is an apocalyptic number.

1666271880 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1666271880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3509251200).

1666271880 is an abundant number, since it is smaller than the sum of its proper divisors (5352230520).

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

1666271880 is a wasteful number, since it uses less digits than its factorization.

1666271880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2733 (or 2726 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 45.

The square root of 1666271880 is about 40819.9936305728. The cubic root of 1666271880 is about 1185.5374798341.

The spelling of 1666271880 in words is "one billion, six hundred sixty-six million, two hundred seventy-one thousand, eight hundred eighty".