20661567 has 16 divisors (see below), whose sum is σ = 28885248. Its totient is φ = 13112000.

The previous prime is 20661551. The next prime is 20661583. The reversal of 20661567 is 76516602.

It is an interprime number because it is at equal distance from previous prime (20661551) and next prime (20661583).

It is a cyclic number.

It is not a de Polignac number, because 20661567 - 2⁴ = 20661551 is a prime.

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 15 ways as a sum of consecutive naturals, for example, 16723 + ... + 17915.

It is an arithmetic number, because the mean of its divisors is an integer number (1805328).

Almost surely, 2^20661567 is an apocalyptic number.

20661567 is a deficient number, since it is larger than the sum of its proper divisors (8223681).

20661567 is a wasteful number, since it uses less digits than its factorization.

20661567 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1470.

The product of its (nonzero) digits is 15120, while the sum is 33.

The square root of 20661567 is about 4545.4996425036. The cubic root of 20661567 is about 274.4023029823.

The spelling of 20661567 in words is "twenty million, six hundred sixty-one thousand, five hundred sixty-seven".