21850091 has 4 divisors (see below), whose sum is σ = 22440672. Its totient is φ = 21259512.

The previous prime is 21850061. The next prime is 21850093. The reversal of 21850091 is 19005812.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21850091 - 2⁶ = 21850027 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 21850091.

It is not an unprimeable number, because it can be changed into a prime (21850093) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 295235 + ... + 295308.

It is an arithmetic number, because the mean of its divisors is an integer number (5610168).

Almost surely, 2^21850091 is an apocalyptic number.

21850091 is a deficient number, since it is larger than the sum of its proper divisors (590581).

21850091 is an equidigital number, since it uses as much as digits as its factorization.

21850091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 590580.

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 21850091 is about 4674.4080908710. The cubic root of 21850091 is about 279.5660412106.

The spelling of 21850091 in words is "twenty-one million, eight hundred fifty thousand, ninety-one".