20660861 has 4 divisors (see below), whose sum is σ = 22250172. Its totient is φ = 19071552.

The previous prime is 20660851. The next prime is 20660869. The reversal of 20660861 is 16806602.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6175225 + 14485636 = 2485^2 + 3806^2 .

It is a cyclic number.

It is not a de Polignac number, because 20660861 - 2¹⁸ = 20398717 is a prime.

It is a super-2 number, since 2×20660861² = 853742354522642, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20660869) 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, 794636 + ... + 794661.

It is an arithmetic number, because the mean of its divisors is an integer number (5562543).

Almost surely, 2^20660861 is an apocalyptic number.

It is an amenable number.

20660861 is a deficient number, since it is larger than the sum of its proper divisors (1589311).

20660861 is a wasteful number, since it uses less digits than its factorization.

20660861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1589310.

The product of its (nonzero) digits is 3456, while the sum is 29.

The square root of 20660861 is about 4545.4219826106. The cubic root of 20660861 is about 274.3991775299.

The spelling of 20660861 in words is "twenty million, six hundred sixty thousand, eight hundred sixty-one".