21361849 has 4 divisors (see below), whose sum is σ = 21378420. Its totient is φ = 21345280.

The previous prime is 21361831. The next prime is 21361853. The reversal of 21361849 is 94816312.

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 4494400 + 16867449 = 2120^2 + 4107^2 .

It is a cyclic number.

It is not a de Polignac number, because 21361849 - 2⁵ = 21361817 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21361889) 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, 6172 + ... + 8989.

It is an arithmetic number, because the mean of its divisors is an integer number (5344605).

Almost surely, 2^21361849 is an apocalyptic number.

It is an amenable number.

21361849 is a deficient number, since it is larger than the sum of its proper divisors (16571).

21361849 is a wasteful number, since it uses less digits than its factorization.

21361849 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16570.

The product of its digits is 10368, while the sum is 34.

The square root of 21361849 is about 4621.8880341263. Note that the first 3 decimals coincide. The cubic root of 21361849 is about 277.4680275909.

The spelling of 21361849 in words is "twenty-one million, three hundred sixty-one thousand, eight hundred forty-nine".