21849817 has 12 divisors (see below), whose sum is σ = 24131520. Its totient is φ = 19768760.

The previous prime is 21849809. The next prime is 21849857. The reversal of 21849817 is 71894812.

It is a happy number.

It is not a de Polignac number, because 21849817 - 2³ = 21849809 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21849817.

It is not an unprimeable number, because it can be changed into a prime (21849857) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 43188 + ... + 43690.

It is an arithmetic number, because the mean of its divisors is an integer number (2010960).

Almost surely, 2^21849817 is an apocalyptic number.

It is an amenable number.

21849817 is a deficient number, since it is larger than the sum of its proper divisors (2281703).

21849817 is a wasteful number, since it uses less digits than its factorization.

21849817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 884 (or 873 counting only the distinct ones).

The product of its digits is 32256, while the sum is 40.

The square root of 21849817 is about 4674.3787822555. The cubic root of 21849817 is about 279.5648726202.

The spelling of 21849817 in words is "twenty-one million, eight hundred forty-nine thousand, eight hundred seventeen".