21850517 has 6 divisors (see below), whose sum is σ = 23660802. Its totient is φ = 20169552.

The previous prime is 21850489. The next prime is 21850547. The reversal of 21850517 is 71505812.

It can be written as a sum of positive squares in 3 ways, for example, as 78961 + 21771556 = 281^2 + 4666^2 .

It is not a de Polignac number, because 21850517 - 2⁶ = 21850453 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21850517.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21850547) 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 5 ways as a sum of consecutive naturals, for example, 64478 + ... + 64815.

It is an arithmetic number, because the mean of its divisors is an integer number (3943467).

Almost surely, 2^21850517 is an apocalyptic number.

It is an amenable number.

21850517 is a deficient number, since it is larger than the sum of its proper divisors (1810285).

21850517 is a wasteful number, since it uses less digits than its factorization.

21850517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129319 (or 129306 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 29.

The square root of 21850517 is about 4674.4536579155. The cubic root of 21850517 is about 279.5678580506.

The spelling of 21850517 in words is "twenty-one million, eight hundred fifty thousand, five hundred seventeen".