20663666 has 4 divisors (see below), whose sum is σ = 30995502. Its totient is φ = 10331832.

The previous prime is 20663651. The next prime is 20663677. The reversal of 20663666 is 66636602.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 10923025 + 9740641 = 3305^2 + 3121^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5165915 + ... + 5165918.

Almost surely, 2^20663666 is an apocalyptic number.

20663666 is a deficient number, since it is larger than the sum of its proper divisors (10331836).

20663666 is a wasteful number, since it uses less digits than its factorization.

20663666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10331835.

The product of its (nonzero) digits is 46656, while the sum is 35.

The square root of 20663666 is about 4545.7305243492. The cubic root of 20663666 is about 274.4115948062.

The spelling of 20663666 in words is "twenty million, six hundred sixty-three thousand, six hundred sixty-six".