21149709 has 8 divisors (see below), whose sum is σ = 32228160. Its totient is φ = 12085536.

The previous prime is 21149699. The next prime is 21149731. The reversal of 21149709 is 90794112.

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

It is not a de Polignac number, because 21149709 - 2⁹ = 21149197 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21149709.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21149509) 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, 503544 + ... + 503585.

It is an arithmetic number, because the mean of its divisors is an integer number (4028520).

Almost surely, 2^21149709 is an apocalyptic number.

It is an amenable number.

21149709 is a deficient number, since it is larger than the sum of its proper divisors (11078451).

21149709 is a wasteful number, since it uses less digits than its factorization.

21149709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1007139.

The product of its (nonzero) digits is 4536, while the sum is 33.

The square root of 21149709 is about 4598.8812770064. The cubic root of 21149709 is about 276.5464781743.

The spelling of 21149709 in words is "twenty-one million, one hundred forty-nine thousand, seven hundred nine".