20544787997 has 4 divisors (see below), whose sum is σ = 21753304956. Its totient is φ = 19336271040.

The previous prime is 20544787993. The next prime is 20544788021. The reversal of 20544787997 is 79978744502.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 13460872441 + 7083915556 = 116021^2 + 84166^2 .

It is a cyclic number.

It is not a de Polignac number, because 20544787997 - 2² = 20544787993 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 (20544787993) 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, 604258454 + ... + 604258487.

It is an arithmetic number, because the mean of its divisors is an integer number (5438326239).

Almost surely, 2^20544787997 is an apocalyptic number.

It is an amenable number.

20544787997 is a deficient number, since it is larger than the sum of its proper divisors (1208516959).

20544787997 is a wasteful number, since it uses less digits than its factorization.

20544787997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1208516958.

The product of its (nonzero) digits is 35562240, while the sum is 62.

The spelling of 20544787997 in words is "twenty billion, five hundred forty-four million, seven hundred eighty-seven thousand, nine hundred ninety-seven".