20660551 has 4 divisors (see below), whose sum is σ = 20674600. Its totient is φ = 20646504.

The previous prime is 20660527. The next prime is 20660567. The reversal of 20660551 is 15506602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15506602 = 2 ⋅7753301.

It is a cyclic number.

It is not a de Polignac number, because 20660551 - 2¹¹ = 20658503 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 (20660501) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4521 + ... + 7858.

It is an arithmetic number, because the mean of its divisors is an integer number (5168650).

Almost surely, 2^20660551 is an apocalyptic number.

20660551 is a deficient number, since it is larger than the sum of its proper divisors (14049).

20660551 is a wasteful number, since it uses less digits than its factorization.

20660551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14048.

The product of its (nonzero) digits is 1800, while the sum is 25.

The square root of 20660551 is about 4545.3878822384. The cubic root of 20660551 is about 274.3978051416.

The spelling of 20660551 in words is "twenty million, six hundred sixty thousand, five hundred fifty-one".