23135721 has 16 divisors (see below), whose sum is σ = 35328384. Its totient is φ = 13192704.

The previous prime is 23135713. The next prime is 23135737. The reversal of 23135721 is 12753132.

It is not a de Polignac number, because 23135721 - 2³ = 23135713 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 23135691 and 23135700.

It is not an unprimeable number, because it can be changed into a prime (23135701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13315 + ... + 14951.

It is an arithmetic number, because the mean of its divisors is an integer number (2208024).

Almost surely, 2^23135721 is an apocalyptic number.

23135721 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

23135721 is a deficient number, since it is larger than the sum of its proper divisors (12192663).

23135721 is a wasteful number, since it uses less digits than its factorization.

23135721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2320.

The product of its digits is 1260, while the sum is 24.

The square root of 23135721 is about 4809.9606027493. The cubic root of 23135721 is about 284.9449816849.

Adding to 23135721 its reverse (12753132), we get a palindrome (35888853).

The spelling of 23135721 in words is "twenty-three million, one hundred thirty-five thousand, seven hundred twenty-one".