21649407 has 12 divisors (see below), whose sum is σ = 31257864. Its totient is φ = 13322400.

The previous prime is 21649361. The next prime is 21649429. The reversal of 21649407 is 70494612.

It is a happy number.

It is not a de Polignac number, because 21649407 - 2¹⁰ = 21648383 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21649447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20844 + ... + 21857.

It is an arithmetic number, because the mean of its divisors is an integer number (2604822).

Almost surely, 2^21649407 is an apocalyptic number.

21649407 is a deficient number, since it is larger than the sum of its proper divisors (9608457).

21649407 is a wasteful number, since it uses less digits than its factorization.

21649407 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42730 (or 42717 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 33.

The square root of 21649407 is about 4652.8923262848. The cubic root of 21649407 is about 278.7075081188.

The spelling of 21649407 in words is "twenty-one million, six hundred forty-nine thousand, four hundred seven".