21774383687809 has 9 divisors (see below), whose sum is σ = 22551255718147. Its totient is φ = 21023412214504.

The previous prime is 21774383687737. The next prime is 21774383687813. The reversal of 21774383687809 is 90878638347712.

The square root of 21774383687809 is 4666303.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 11417958628209 + 10356425059600 = 3379047^2 + 3218140^2 .

It is not a de Polignac number, because 21774383687809 - 2⁹ = 21774383687297 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21774383687509) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 135242334 + ... + 135403240.

Almost surely, 2^{21774383687809} is an apocalyptic number.

21774383687809 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

21774383687809 is the 4666303-rd square number.

21774383687809 is the 2333152-nd centered octagonal number.

It is an amenable number.

21774383687809 is a deficient number, since it is larger than the sum of its proper divisors (776872030338).

21774383687809 is an frugal number, since it uses more digits than its factorization.

21774383687809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 321872 (or 160936 counting only the distinct ones).

The product of its (nonzero) digits is 682795008, while the sum is 73.

The spelling of 21774383687809 in words is "twenty-one trillion, seven hundred seventy-four billion, three hundred eighty-three million, six hundred eighty-seven thousand, eight hundred nine".