21409747 has 8 divisors (see below), whose sum is σ = 22164480. Its totient is φ = 20659080.

The previous prime is 21409733. The next prime is 21409777. The reversal of 21409747 is 74790412.

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 21409747 - 2²³ = 13021139 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21409727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12954 + ... + 14512.

It is an arithmetic number, because the mean of its divisors is an integer number (2770560).

Almost surely, 2^21409747 is an apocalyptic number.

21409747 is a deficient number, since it is larger than the sum of its proper divisors (754733).

21409747 is a wasteful number, since it uses less digits than its factorization.

21409747 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2033.

The product of its (nonzero) digits is 14112, while the sum is 34.

The square root of 21409747 is about 4627.0667814502. The cubic root of 21409747 is about 277.6752543901.

The spelling of 21409747 in words is "twenty-one million, four hundred nine thousand, seven hundred forty-seven".