1997406666 has 12 divisors (see below), whose sum is σ = 4327714482. Its totient is φ = 665802216.

The previous prime is 1997406661. The next prime is 1997406667. The reversal of 1997406666 is 6666047991.

It can be written as a sum of positive squares in only one way, i.e., 1400630625 + 596776041 = 37425^2 + 24429^2 .

It is not an unprimeable number, because it can be changed into a prime (1997406661) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 55483501 + ... + 55483536.

Almost surely, 2^1997406666 is an apocalyptic number.

1997406666 is an abundant number, since it is smaller than the sum of its proper divisors (2330307816).

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

1997406666 is a wasteful number, since it uses less digits than its factorization.

1997406666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110967045 (or 110967042 counting only the distinct ones).

The product of its (nonzero) digits is 2939328, while the sum is 54.

The square root of 1997406666 is about 44692.3557893293. The cubic root of 1997406666 is about 1259.3762483356.

The spelling of 1997406666 in words is "one billion, nine hundred ninety-seven million, four hundred six thousand, six hundred sixty-six".