23921509 has 4 divisors (see below), whose sum is σ = 24190380. Its totient is φ = 23652640.

The previous prime is 23921489. The next prime is 23921519. The reversal of 23921509 is 90512932.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4972900 + 18948609 = 2230^2 + 4353^2 .

It is not a de Polignac number, because 23921509 - 2¹³ = 23913317 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (23921519) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 134302 + ... + 134479.

It is an arithmetic number, because the mean of its divisors is an integer number (6047595).

Almost surely, 2^23921509 is an apocalyptic number.

It is an amenable number.

23921509 is a deficient number, since it is larger than the sum of its proper divisors (268871).

23921509 is an equidigital number, since it uses as much as digits as its factorization.

23921509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 268870.

The product of its (nonzero) digits is 4860, while the sum is 31.

The square root of 23921509 is about 4890.9619708192. The cubic root of 23921509 is about 288.1351161588.

The spelling of 23921509 in words is "twenty-three million, nine hundred twenty-one thousand, five hundred nine".