21649005 has 64 divisors (see below), whose sum is σ = 45465600. Its totient is φ = 9564480.

The previous prime is 21648997. The next prime is 21649031. The reversal of 21649005 is 50094612.

It is not a de Polignac number, because 21649005 - 2³ = 21648997 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a self number, because there is not a number n which added to its sum of digits gives 21649005.

It is a congruent number.

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 28926 + ... + 29664.

It is an arithmetic number, because the mean of its divisors is an integer number (710400).

Almost surely, 2^21649005 is an apocalyptic number.

It is an amenable number.

21649005 is an abundant number, since it is smaller than the sum of its proper divisors (23816595).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21649005 is a wasteful number, since it uses less digits than its factorization.

21649005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 791 (or 785 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 21649005 is about 4652.8491271478. The cubic root of 21649005 is about 278.7057830351.

The spelling of 21649005 in words is "twenty-one million, six hundred forty-nine thousand, five".