20664747 has 16 divisors (see below), whose sum is σ = 30804480. Its totient is φ = 13691016.

The previous prime is 20664737. The next prime is 20664781. The reversal of 20664747 is 74746602.

20664747 is a `hidden beast` number, since 2 + 0 + 6 + 647 + 4 + 7 = 666.

It is not a de Polignac number, because 20664747 - 2¹¹ = 20662699 is a prime.

It is a super-3 number, since 3×20664747³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (20664727) 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, 2218 + ... + 6800.

It is an arithmetic number, because the mean of its divisors is an integer number (1925280).

Almost surely, 2^20664747 is an apocalyptic number.

20664747 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

20664747 is a deficient number, since it is larger than the sum of its proper divisors (10139733).

20664747 is a wasteful number, since it uses less digits than its factorization.

20664747 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4759 (or 4753 counting only the distinct ones).

The product of its (nonzero) digits is 56448, while the sum is 36.

The square root of 20664747 is about 4545.8494255749. The cubic root of 20664747 is about 274.4163799165.

The spelling of 20664747 in words is "twenty million, six hundred sixty-four thousand, seven hundred forty-seven".