1991666530 has 32 divisors (see below), whose sum is σ = 4134746880. Its totient is φ = 676589760.

The previous prime is 1991666527. The next prime is 1991666539. The reversal of 1991666530 is 356661991.

It is not an unprimeable number, because it can be changed into a prime (1991666539) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 122886 + ... + 138145.

It is an arithmetic number, because the mean of its divisors is an integer number (129210840).

Almost surely, 2^1991666530 is an apocalyptic number.

1991666530 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1991666530 is an abundant number, since it is smaller than the sum of its proper divisors (2143080350).

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

1991666530 is a wasteful number, since it uses less digits than its factorization.

1991666530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 261154.

The product of its (nonzero) digits is 262440, while the sum is 46.

The square root of 1991666530 is about 44628.0912654799. The cubic root of 1991666530 is about 1258.1686947247.

The spelling of 1991666530 in words is "one billion, nine hundred ninety-one million, six hundred sixty-six thousand, five hundred thirty".