20661597 has 18 divisors (see below), whose sum is σ = 32806046. Its totient is φ = 12521520.

The previous prime is 20661587. The next prime is 20661631. The reversal of 20661597 is 79516602.

20661597 is a `hidden beast` number, since 2 + 0 + 6 + 61 + 597 = 666.

It can be written as a sum of positive squares in only one way, i.e., 16475481 + 4186116 = 4059^2 + 2046^2 .

It is not a de Polignac number, because 20661597 - 2¹¹ = 20659549 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20661587) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 8398 + ... + 10575.

Almost surely, 2^20661597 is an apocalyptic number.

It is an amenable number.

20661597 is a deficient number, since it is larger than the sum of its proper divisors (12144449).

20661597 is a wasteful number, since it uses less digits than its factorization.

20661597 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19001 (or 18987 counting only the distinct ones).

The product of its (nonzero) digits is 22680, while the sum is 36.

The square root of 20661597 is about 4545.5029424696. The cubic root of 20661597 is about 274.4024357903.

It can be divided in two parts, 2066 and 1597, that added together give a palindrome (3663).

The spelling of 20661597 in words is "twenty million, six hundred sixty-one thousand, five hundred ninety-seven".