21155849 has 16 divisors (see below), whose sum is σ = 24984960. Its totient is φ = 17660160.

The previous prime is 21155843. The next prime is 21155861. The reversal of 21155849 is 94855112.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21155849 is a prime.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

Its product of digits (14400) is a multiple of the sum of its prime divisors (800).

It is not an unprimeable number, because it can be changed into a prime (21155843) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 47972 + ... + 48410.

It is an arithmetic number, because the mean of its divisors is an integer number (1561560).

Almost surely, 2^21155849 is an apocalyptic number.

It is an amenable number.

21155849 is a deficient number, since it is larger than the sum of its proper divisors (3829111).

21155849 is a wasteful number, since it uses less digits than its factorization.

21155849 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 800.

The product of its digits is 14400, while the sum is 35.

The square root of 21155849 is about 4599.5487822177. The cubic root of 21155849 is about 276.5732371096.

The spelling of 21155849 in words is "twenty-one million, one hundred fifty-five thousand, eight hundred forty-nine".