20947765 has 4 divisors (see below), whose sum is σ = 25137324. Its totient is φ = 16758208.

The previous prime is 20947741. The next prime is 20947781. The reversal of 20947765 is 56774902.

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 9597604 + 11350161 = 3098^2 + 3369^2 .

It is a cyclic number.

It is not a de Polignac number, because 20947765 - 2⁷ = 20947637 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2094772 + ... + 2094781.

It is an arithmetic number, because the mean of its divisors is an integer number (6284331).

Almost surely, 2^20947765 is an apocalyptic number.

It is an amenable number.

20947765 is a deficient number, since it is larger than the sum of its proper divisors (4189559).

20947765 is an equidigital number, since it uses as much as digits as its factorization.

20947765 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4189558.

The product of its (nonzero) digits is 105840, while the sum is 40.

The square root of 20947765 is about 4576.8728407069. The cubic root of 20947765 is about 275.6634778647.

It can be divided in two parts, 20947 and 765, that added together give a palindrome (21712).

The spelling of 20947765 in words is "twenty million, nine hundred forty-seven thousand, seven hundred sixty-five".