20561619399 has 16 divisors (see below), whose sum is σ = 28054792800. Its totient is φ = 13390356096.

The previous prime is 20561619389. The next prime is 20561619409. The reversal of 20561619399 is 99391616502.

It is an interprime number because it is at equal distance from previous prime (20561619389) and next prime (20561619409).

It is a de Polignac number, because none of the positive numbers 2^k-20561619399 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20561619319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 245944 + ... + 318765.

It is an arithmetic number, because the mean of its divisors is an integer number (1753424550).

Almost surely, 2^20561619399 is an apocalyptic number.

20561619399 is a deficient number, since it is larger than the sum of its proper divisors (7493173401).

20561619399 is a wasteful number, since it uses less digits than its factorization.

20561619399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 564994.

The product of its (nonzero) digits is 787320, while the sum is 51.

The spelling of 20561619399 in words is "twenty billion, five hundred sixty-one million, six hundred nineteen thousand, three hundred ninety-nine".