21191849249 has 4 divisors (see below), whose sum is σ = 21196268100. Its totient is φ = 21187430400.

The previous prime is 21191849243. The next prime is 21191849279. The reversal of 21191849249 is 94294819112.

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 7687782400 + 13504066849 = 87680^2 + 116207^2 .

It is a cyclic number.

It is not a de Polignac number, because 21191849249 - 2¹² = 21191845153 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21191849197 and 21191849206.

It is not an unprimeable number, because it can be changed into a prime (21191849243) 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, 2202224 + ... + 2211825.

It is an arithmetic number, because the mean of its divisors is an integer number (5299067025).

Almost surely, 2^21191849249 is an apocalyptic number.

It is an amenable number.

21191849249 is a deficient number, since it is larger than the sum of its proper divisors (4418851).

21191849249 is an equidigital number, since it uses as much as digits as its factorization.

21191849249 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4418850.

The product of its digits is 373248, while the sum is 50.

The spelling of 21191849249 in words is "twenty-one billion, one hundred ninety-one million, eight hundred forty-nine thousand, two hundred forty-nine".