21125723 has 2 divisors, whose sum is σ = 21125724. Its totient is φ = 21125722.

The previous prime is 21125711. The next prime is 21125729. The reversal of 21125723 is 32752112.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21125723 - 2¹⁰ = 21124699 is a prime.

It is not a weakly prime, because it can be changed into another prime (21125729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10562861 + 10562862.

It is an arithmetic number, because the mean of its divisors is an integer number (10562862).

Almost surely, 2^21125723 is an apocalyptic number.

21125723 is a deficient number, since it is larger than the sum of its proper divisors (1).

21125723 is an equidigital number, since it uses as much as digits as its factorization.

21125723 is an evil number, because the sum of its binary digits is even.

The product of its digits is 840, while the sum is 23.

The square root of 21125723 is about 4596.2727290708. The cubic root of 21125723 is about 276.4418943396.

Adding to 21125723 its reverse (32752112), we get a palindrome (53877835).

The spelling of 21125723 in words is "twenty-one million, one hundred twenty-five thousand, seven hundred twenty-three".