20647764 has 48 divisors (see below), whose sum is σ = 54848640. Its totient is φ = 6713280.

The previous prime is 20647763. The next prime is 20647769. The reversal of 20647764 is 46774602.

20647764 is a `hidden beast` number, since 2 + 0 + 647 + 7 + 6 + 4 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20647763) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2097 + ... + 6759.

It is an arithmetic number, because the mean of its divisors is an integer number (1142680).

Almost surely, 2^20647764 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20647764, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27424320).

20647764 is an abundant number, since it is smaller than the sum of its proper divisors (34200876).

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

20647764 is a wasteful number, since it uses less digits than its factorization.

20647764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4717 (or 4709 counting only the distinct ones).

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

The square root of 20647764 is about 4543.9810739042. The cubic root of 20647764 is about 274.3411843728.

The spelling of 20647764 in words is "twenty million, six hundred forty-seven thousand, seven hundred sixty-four".