20666644 has 6 divisors (see below), whose sum is σ = 36166634. Its totient is φ = 10333320.

The previous prime is 20666621. The next prime is 20666651. The reversal of 20666644 is 44666602.

It can be written as a sum of positive squares in only one way, i.e., 11303044 + 9363600 = 3362^2 + 3060^2 .

It is a super-2 number, since 2×20666644² = 854220348445472, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2583327 + ... + 2583334.

Almost surely, 2^20666644 is an apocalyptic number.

It is an amenable number.

20666644 is a deficient number, since it is larger than the sum of its proper divisors (15499990).

20666644 is a wasteful number, since it uses less digits than its factorization.

20666644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5166665 (or 5166663 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 34.

The square root of 20666644 is about 4546.0580726603. The cubic root of 20666644 is about 274.4247766956.

The spelling of 20666644 in words is "twenty million, six hundred sixty-six thousand, six hundred forty-four".