21142289 has 4 divisors (see below), whose sum is σ = 24162624. Its totient is φ = 18121956.

The previous prime is 21142273. The next prime is 21142291. The reversal of 21142289 is 98224112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21142289 - 2⁴ = 21142273 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21142259) 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, 1510157 + ... + 1510170.

It is an arithmetic number, because the mean of its divisors is an integer number (6040656).

Almost surely, 2^21142289 is an apocalyptic number.

It is an amenable number.

21142289 is a deficient number, since it is larger than the sum of its proper divisors (3020335).

21142289 is an equidigital number, since it uses as much as digits as its factorization.

21142289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3020334.

The product of its digits is 2304, while the sum is 29.

The square root of 21142289 is about 4598.0744883049. The cubic root of 21142289 is about 276.5141339171.

The spelling of 21142289 in words is "twenty-one million, one hundred forty-two thousand, two hundred eighty-nine".