21153423 has 8 divisors (see below), whose sum is σ = 29863728. Its totient is φ = 13272704.

The previous prime is 21153409. The next prime is 21153427. The reversal of 21153423 is 32435112.

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 21153423 - 2⁶ = 21153359 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21153423.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21153427) 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, 207336 + ... + 207437.

It is an arithmetic number, because the mean of its divisors is an integer number (3732966).

Almost surely, 2^21153423 is an apocalyptic number.

21153423 is a deficient number, since it is larger than the sum of its proper divisors (8710305).

21153423 is a wasteful number, since it uses less digits than its factorization.

21153423 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 414793.

The product of its digits is 720, while the sum is 21.

The square root of 21153423 is about 4599.2850531360. The cubic root of 21153423 is about 276.5626648982.

Adding to 21153423 its reverse (32435112), we get a palindrome (53588535).

The spelling of 21153423 in words is "twenty-one million, one hundred fifty-three thousand, four hundred twenty-three".