21153849 has 4 divisors (see below), whose sum is σ = 28205136. Its totient is φ = 14102564.

The previous prime is 21153841. The next prime is 21153851. The reversal of 21153849 is 94835112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21153849 - 2³ = 21153841 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21153841) 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, 3525639 + ... + 3525644.

It is an arithmetic number, because the mean of its divisors is an integer number (7051284).

Almost surely, 2^21153849 is an apocalyptic number.

It is an amenable number.

21153849 is a deficient number, since it is larger than the sum of its proper divisors (7051287).

21153849 is an equidigital number, since it uses as much as digits as its factorization.

21153849 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7051286.

The product of its digits is 8640, while the sum is 33.

The square root of 21153849 is about 4599.3313644485. The cubic root of 21153849 is about 276.5645214127.

The spelling of 21153849 in words is "twenty-one million, one hundred fifty-three thousand, eight hundred forty-nine".