20818440451 has 4 divisors (see below), whose sum is σ = 20835464112. Its totient is φ = 20801416792.

The previous prime is 20818440421. The next prime is 20818440469. The reversal of 20818440451 is 15404481802.

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 20818440451 - 2²¹ = 20816343299 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20818440451.

It is not an unprimeable number, because it can be changed into a prime (20818440421) 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 3 ways as a sum of consecutive naturals, for example, 8509996 + ... + 8512441.

It is an arithmetic number, because the mean of its divisors is an integer number (5208866028).

Almost surely, 2^20818440451 is an apocalyptic number.

20818440451 is a deficient number, since it is larger than the sum of its proper divisors (17023661).

20818440451 is a wasteful number, since it uses less digits than its factorization.

20818440451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17023660.

The product of its (nonzero) digits is 40960, while the sum is 37.

The spelling of 20818440451 in words is "twenty billion, eight hundred eighteen million, four hundred forty thousand, four hundred fifty-one".