21274509 has 16 divisors (see below), whose sum is σ = 29998080. Its totient is φ = 13374000.

The previous prime is 21274507. The next prime is 21274529. The reversal of 21274509 is 90547212.

It is not a de Polignac number, because 21274509 - 2¹ = 21274507 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21274507) 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 15 ways as a sum of consecutive naturals, for example, 13564 + ... + 15050.

It is an arithmetic number, because the mean of its divisors is an integer number (1874880).

Almost surely, 2^21274509 is an apocalyptic number.

It is an amenable number.

21274509 is a deficient number, since it is larger than the sum of its proper divisors (8723571).

21274509 is a wasteful number, since it uses less digits than its factorization.

21274509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1760.

The product of its (nonzero) digits is 5040, while the sum is 30.

The square root of 21274509 is about 4612.4298368647. The cubic root of 21274509 is about 277.0893593629.

The spelling of 21274509 in words is "twenty-one million, two hundred seventy-four thousand, five hundred nine".