23015721 has 4 divisors (see below), whose sum is σ = 30687632. Its totient is φ = 15343812.

The previous prime is 23015717. The next prime is 23015749. The reversal of 23015721 is 12751032.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 23015721 - 2² = 23015717 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (23015701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3835951 + ... + 3835956.

It is an arithmetic number, because the mean of its divisors is an integer number (7671908).

Almost surely, 2^23015721 is an apocalyptic number.

It is an amenable number.

23015721 is a deficient number, since it is larger than the sum of its proper divisors (7671911).

23015721 is an equidigital number, since it uses as much as digits as its factorization.

23015721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7671910.

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 23015721 is about 4797.4702708824. The cubic root of 23015721 is about 284.4514780580.

Adding to 23015721 its reverse (12751032), we get a palindrome (35766753).

It can be divided in two parts, 230 and 15721, that added together give a palindrome (15951).

The spelling of 23015721 in words is "twenty-three million, fifteen thousand, seven hundred twenty-one".