21031259 has 4 divisors (see below), whose sum is σ = 21043704. Its totient is φ = 21018816.

The previous prime is 21031253. The next prime is 21031277. The reversal of 21031259 is 95213012.

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

It is a cyclic number.

It is not a de Polignac number, because 21031259 - 2¹⁶ = 20965723 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21031253) 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, 3197 + ... + 7230.

It is an arithmetic number, because the mean of its divisors is an integer number (5260926).

Almost surely, 2^21031259 is an apocalyptic number.

21031259 is a deficient number, since it is larger than the sum of its proper divisors (12445).

21031259 is a wasteful number, since it uses less digits than its factorization.

21031259 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12444.

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 21031259 is about 4585.9850632116. The cubic root of 21031259 is about 276.0292405833.

The spelling of 21031259 in words is "twenty-one million, thirty-one thousand, two hundred fifty-nine".