21289019 has 4 divisors (see below), whose sum is σ = 21320520. Its totient is φ = 21257520.

The previous prime is 21289001. The next prime is 21289027. The reversal of 21289019 is 91098212.

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 21289019 - 2⁸ = 21288763 is a prime.

It is a super-2 number, since 2×21289019² = 906444659964722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21289069) 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, 14714 + ... + 16095.

It is an arithmetic number, because the mean of its divisors is an integer number (5330130).

Almost surely, 2^21289019 is an apocalyptic number.

21289019 is a deficient number, since it is larger than the sum of its proper divisors (31501).

21289019 is an equidigital number, since it uses as much as digits as its factorization.

21289019 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31500.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 21289019 is about 4614.0024924137. The cubic root of 21289019 is about 277.1523401019.

The spelling of 21289019 in words is "twenty-one million, two hundred eighty-nine thousand, nineteen".