20867915785 has 4 divisors (see below), whose sum is σ = 25041498948. Its totient is φ = 16694332624.

The previous prime is 20867915779. The next prime is 20867915813. The reversal of 20867915785 is 58751976802.

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 3919260816 + 16948654969 = 62604^2 + 130187^2 .

It is a cyclic number.

It is not a de Polignac number, because 20867915785 - 2⁹ = 20867915273 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2086791574 + ... + 2086791583.

It is an arithmetic number, because the mean of its divisors is an integer number (6260374737).

Almost surely, 2^20867915785 is an apocalyptic number.

It is an amenable number.

20867915785 is a deficient number, since it is larger than the sum of its proper divisors (4173583163).

20867915785 is an equidigital number, since it uses as much as digits as its factorization.

20867915785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4173583162.

The product of its (nonzero) digits is 8467200, while the sum is 58.

The spelling of 20867915785 in words is "twenty billion, eight hundred sixty-seven million, nine hundred fifteen thousand, seven hundred eighty-five".