21250019 has 4 divisors (see below), whose sum is σ = 24285744. Its totient is φ = 18214296.

The previous prime is 21250007. The next prime is 21250039. The reversal of 21250019 is 91005212.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21250019 is a prime.

It is a super-2 number, since 2×21250019² = 903126615000722, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21250039) 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, 1517852 + ... + 1517865.

It is an arithmetic number, because the mean of its divisors is an integer number (6071436).

Almost surely, 2^21250019 is an apocalyptic number.

21250019 is a deficient number, since it is larger than the sum of its proper divisors (3035725).

21250019 is an equidigital number, since it uses as much as digits as its factorization.

21250019 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3035724.

The product of its (nonzero) digits is 180, while the sum is 20.

The square root of 21250019 is about 4609.7742894853. The cubic root of 21250019 is about 276.9829953895.

The spelling of 21250019 in words is "twenty-one million, two hundred fifty thousand, nineteen".