21850509 has 8 divisors (see below), whose sum is σ = 29569120. Its totient is φ = 14349456.

The previous prime is 21850489. The next prime is 21850547. The reversal of 21850509 is 90505812.

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

It is not a de Polignac number, because 21850509 - 2²⁰ = 20801933 is a prime.

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

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21851509) 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 7 ways as a sum of consecutive naturals, for example, 54154 + ... + 54555.

It is an arithmetic number, because the mean of its divisors is an integer number (3696140).

Almost surely, 2^21850509 is an apocalyptic number.

It is an amenable number.

21850509 is a deficient number, since it is larger than the sum of its proper divisors (7718611).

21850509 is a wasteful number, since it uses less digits than its factorization.

21850509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108779.

The product of its (nonzero) digits is 3600, while the sum is 30.

The square root of 21850509 is about 4674.4528022005. The cubic root of 21850509 is about 279.5678239318.

The spelling of 21850509 in words is "twenty-one million, eight hundred fifty thousand, five hundred nine".