21162566749 has 8 divisors (see below), whose sum is σ = 21898924920. Its totient is φ = 20426649600.

The previous prime is 21162566729. The next prime is 21162566759. The reversal of 21162566749 is 94766526112.

It can be written as a sum of positive squares in 4 ways, for example, as 3058864249 + 18103702500 = 55307^2 + 134550^2 .

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 21162566749 - 2⁵ = 21162566717 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 (21162566729) 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, 11092 + ... + 206029.

It is an arithmetic number, because the mean of its divisors is an integer number (2737365615).

Almost surely, 2^21162566749 is an apocalyptic number.

21162566749 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21162566749 is a deficient number, since it is larger than the sum of its proper divisors (736358171).

21162566749 is a wasteful number, since it uses less digits than its factorization.

21162566749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220511.

The product of its digits is 1088640, while the sum is 49.

The spelling of 21162566749 in words is "twenty-one billion, one hundred sixty-two million, five hundred sixty-six thousand, seven hundred forty-nine".