20261663 has 4 divisors (see below), whose sum is σ = 20295120. Its totient is φ = 20228208.

The previous prime is 20261629. The next prime is 20261687. The reversal of 20261663 is 36616202.

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

It is a cyclic number.

It is not a de Polignac number, because 20261663 - 2⁶ = 20261599 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 (20261363) 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, 15803 + ... + 17036.

It is an arithmetic number, because the mean of its divisors is an integer number (5073780).

Almost surely, 2^20261663 is an apocalyptic number.

20261663 is a deficient number, since it is larger than the sum of its proper divisors (33457).

20261663 is an equidigital number, since it uses as much as digits as its factorization.

20261663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33456.

The product of its (nonzero) digits is 2592, while the sum is 26.

The square root of 20261663 is about 4501.2957023506. The cubic root of 20261663 is about 272.6204074682.

Adding to 20261663 its reverse (36616202), we get a palindrome (56877865).

The spelling of 20261663 in words is "twenty million, two hundred sixty-one thousand, six hundred sixty-three".