21711402785 has 4 divisors (see below), whose sum is σ = 26053683348. Its totient is φ = 17369122224.

The previous prime is 21711402781. The next prime is 21711402793. The reversal of 21711402785 is 58720411712.

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 13732089856 + 7979312929 = 117184^2 + 89327^2 .

It is a cyclic number.

It is not a de Polignac number, because 21711402785 - 2² = 21711402781 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21711402781) 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, 2171140274 + ... + 2171140283.

It is an arithmetic number, because the mean of its divisors is an integer number (6513420837).

Almost surely, 2^21711402785 is an apocalyptic number.

It is an amenable number.

21711402785 is a deficient number, since it is larger than the sum of its proper divisors (4342280563).

21711402785 is an equidigital number, since it uses as much as digits as its factorization.

21711402785 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4342280562.

The product of its (nonzero) digits is 31360, while the sum is 38.

The spelling of 21711402785 in words is "twenty-one billion, seven hundred eleven million, four hundred two thousand, seven hundred eighty-five".