20561768 has 8 divisors (see below), whose sum is σ = 38553330. Its totient is φ = 10280880.

The previous prime is 20561767. The next prime is 20561771. The reversal of 20561768 is 86716502.

It can be written as a sum of positive squares in only one way, i.e., 20268004 + 293764 = 4502^2 + 542^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (20561767) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1285103 + ... + 1285118.

Almost surely, 2^20561768 is an apocalyptic number.

It is an amenable number.

20561768 is a deficient number, since it is larger than the sum of its proper divisors (17991562).

20561768 is a wasteful number, since it uses less digits than its factorization.

20561768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2570227 (or 2570223 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 20561768 is about 4534.5085731532. The cubic root of 20561768 is about 273.9597859536.

The spelling of 20561768 in words is "twenty million, five hundred sixty-one thousand, seven hundred sixty-eight".