21649837 has 8 divisors (see below), whose sum is σ = 23664960. Its totient is φ = 19642560.

The previous prime is 21649819. The next prime is 21649861. The reversal of 21649837 is 73894612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21649837 - 2¹¹ = 21647789 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21649837.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21649867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4864 + ... + 8182.

It is an arithmetic number, because the mean of its divisors is an integer number (2958120).

Almost surely, 2^21649837 is an apocalyptic number.

It is an amenable number.

21649837 is a deficient number, since it is larger than the sum of its proper divisors (2015123).

21649837 is a wasteful number, since it uses less digits than its factorization.

21649837 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3923.

The product of its digits is 72576, while the sum is 40.

The square root of 21649837 is about 4652.9385338730. The cubic root of 21649837 is about 278.7093533338.

The spelling of 21649837 in words is "twenty-one million, six hundred forty-nine thousand, eight hundred thirty-seven".