21234567 has 4 divisors (see below), whose sum is σ = 28312760. Its totient is φ = 14156376.

The previous prime is 21234541. The next prime is 21234593. The reversal of 21234567 is 76543212.

21234567 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.

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

It is an interprime number because it is at equal distance from previous prime (21234541) and next prime (21234593).

It is not a de Polignac number, because 21234567 - 2¹⁹ = 20710279 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21234067) 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, 3539092 + ... + 3539097.

It is an arithmetic number, because the mean of its divisors is an integer number (7078190).

Almost surely, 2^21234567 is an apocalyptic number.

21234567 is a deficient number, since it is larger than the sum of its proper divisors (7078193).

21234567 is an equidigital number, since it uses as much as digits as its factorization.

21234567 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7078192.

The product of its digits is 10080, while the sum is 30.

The square root of 21234567 is about 4608.0979807291. The cubic root of 21234567 is about 276.9158428369.

Adding to 21234567 its reverse (76543212), we get a palindrome (97777779).

The spelling of 21234567 in words is "twenty-one million, two hundred thirty-four thousand, five hundred sixty-seven".