20345551 has 4 divisors (see below), whose sum is σ = 20356504. Its totient is φ = 20334600.

The previous prime is 20345531. The next prime is 20345573. The reversal of 20345551 is 15554302.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20345551 - 2⁵ = 20345519 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 (20345531) 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, 1920 + ... + 6661.

It is an arithmetic number, because the mean of its divisors is an integer number (5089126).

Almost surely, 2^20345551 is an apocalyptic number.

20345551 is a deficient number, since it is larger than the sum of its proper divisors (10953).

20345551 is an equidigital number, since it uses as much as digits as its factorization.

20345551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10952.

The product of its (nonzero) digits is 3000, while the sum is 25.

The square root of 20345551 is about 4510.6042832419. The cubic root of 20345551 is about 272.9961267324.

Adding to 20345551 its reverse (15554302), we get a palindrome (35899853).

It can be divided in two parts, 203 and 45551, that added together give a palindrome (45754).

The spelling of 20345551 in words is "twenty million, three hundred forty-five thousand, five hundred fifty-one".