20544642551 has 4 divisors (see below), whose sum is σ = 20545633152. Its totient is φ = 20543651952.

The previous prime is 20544642541. The next prime is 20544642571. The reversal of 20544642551 is 15524644502.

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 20544642551 - 2¹⁰ = 20544641527 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 (20544642541) 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, 463511 + ... + 505896.

It is an arithmetic number, because the mean of its divisors is an integer number (5136408288).

Almost surely, 2^20544642551 is an apocalyptic number.

20544642551 is a deficient number, since it is larger than the sum of its proper divisors (990601).

20544642551 is an equidigital number, since it uses as much as digits as its factorization.

20544642551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 990600.

The product of its (nonzero) digits is 192000, while the sum is 38.

The spelling of 20544642551 in words is "twenty billion, five hundred forty-four million, six hundred forty-two thousand, five hundred fifty-one".