20987764493 has 8 divisors (see below), whose sum is σ = 22067408280. Its totient is φ = 19931849280.

The previous prime is 20987764481. The next prime is 20987764513. The reversal of 20987764493 is 39446778902.

It can be written as a sum of positive squares in 4 ways, for example, as 3984386884 + 17003377609 = 63122^2 + 130397^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20987764493 - 2¹⁴ = 20987748109 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 (20987464493) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5930330 + ... + 5933867.

It is an arithmetic number, because the mean of its divisors is an integer number (2758426035).

Almost surely, 2^20987764493 is an apocalyptic number.

It is an amenable number.

20987764493 is a deficient number, since it is larger than the sum of its proper divisors (1079643787).

20987764493 is a wasteful number, since it uses less digits than its factorization.

20987764493 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11864287.

The product of its (nonzero) digits is 18289152, while the sum is 59.

The spelling of 20987764493 in words is "twenty billion, nine hundred eighty-seven million, seven hundred sixty-four thousand, four hundred ninety-three".