21072423 has 8 divisors (see below), whose sum is σ = 28119168. Its totient is φ = 14036984.

The previous prime is 21072421. The next prime is 21072431. The reversal of 21072423 is 32427012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21072423 - 2¹ = 21072421 is a prime.

It is a super-2 number, since 2×21072423² = 888094022181858, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21072423.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21072421) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3640 + ... + 7442.

It is an arithmetic number, because the mean of its divisors is an integer number (3514896).

Almost surely, 2^21072423 is an apocalyptic number.

21072423 is a deficient number, since it is larger than the sum of its proper divisors (7046745).

21072423 is a wasteful number, since it uses less digits than its factorization.

21072423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5653.

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 21072423 is about 4590.4708908782. The cubic root of 21072423 is about 276.2092117799.

Adding to 21072423 its reverse (32427012), we get a palindrome (53499435).

The spelling of 21072423 in words is "twenty-one million, seventy-two thousand, four hundred twenty-three".