20966861 has 4 divisors (see below), whose sum is σ = 22070400. Its totient is φ = 19863324.

The previous prime is 20966851. The next prime is 20966903. The reversal of 20966861 is 16866902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20966861 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20966821) 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, 551741 + ... + 551778.

It is an arithmetic number, because the mean of its divisors is an integer number (5517600).

Almost surely, 2^20966861 is an apocalyptic number.

It is an amenable number.

20966861 is a deficient number, since it is larger than the sum of its proper divisors (1103539).

20966861 is a wasteful number, since it uses less digits than its factorization.

20966861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1103538.

The product of its (nonzero) digits is 31104, while the sum is 38.

The square root of 20966861 is about 4578.9585060361. The cubic root of 20966861 is about 275.7472174428.

The spelling of 20966861 in words is "twenty million, nine hundred sixty-six thousand, eight hundred sixty-one".