20405766 has 16 divisors (see below), whose sum is σ = 41174064. Its totient is φ = 6741504.

The previous prime is 20405743. The next prime is 20405767. The reversal of 20405766 is 66750402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20405767) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14371 + ... + 15726.

It is an arithmetic number, because the mean of its divisors is an integer number (2573379).

Almost surely, 2^20405766 is an apocalyptic number.

20405766 is an abundant number, since it is smaller than the sum of its proper divisors (20768298).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20405766 is a wasteful number, since it uses less digits than its factorization.

20405766 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30215.

The product of its (nonzero) digits is 10080, while the sum is 30.

The square root of 20405766 is about 4517.2741780857. The cubic root of 20405766 is about 273.2651826259.

The spelling of 20405766 in words is "twenty million, four hundred five thousand, seven hundred sixty-six".