21840849 has 6 divisors (see below), whose sum is σ = 31547906. Its totient is φ = 14560560.

The previous prime is 21840829. The next prime is 21840851. The reversal of 21840849 is 94804812.

It can be written as a sum of positive squares in only one way, i.e., 21790224 + 50625 = 4668^2 + 225^2 .

It is not a de Polignac number, because 21840849 - 2⁵ = 21840817 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21840809) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1213372 + ... + 1213389.

Almost surely, 2^21840849 is an apocalyptic number.

It is an amenable number.

21840849 is a deficient number, since it is larger than the sum of its proper divisors (9707057).

21840849 is a wasteful number, since it uses less digits than its factorization.

21840849 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2426767 (or 2426764 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 36.

The square root of 21840849 is about 4673.4194119510. The cubic root of 21840849 is about 279.5266193500.

The spelling of 21840849 in words is "twenty-one million, eight hundred forty thousand, eight hundred forty-nine".