20440421551 has 4 divisors (see below), whose sum is σ = 22298641704. Its totient is φ = 18582201400.

The previous prime is 20440421549. The next prime is 20440421579. The reversal of 20440421551 is 15512404402.

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 20440421551 - 2¹ = 20440421549 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 (20440421951) 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, 929110060 + ... + 929110081.

It is an arithmetic number, because the mean of its divisors is an integer number (5574660426).

Almost surely, 2^20440421551 is an apocalyptic number.

20440421551 is a deficient number, since it is larger than the sum of its proper divisors (1858220153).

20440421551 is a wasteful number, since it uses less digits than its factorization.

20440421551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1858220152.

The product of its (nonzero) digits is 6400, while the sum is 28.

Adding to 20440421551 its reverse (15512404402), we get a palindrome (35952825953).

The spelling of 20440421551 in words is "twenty billion, four hundred forty million, four hundred twenty-one thousand, five hundred fifty-one".