21258739 has 8 divisors (see below), whose sum is σ = 23351040. Its totient is φ = 19263816.

The previous prime is 21258733. The next prime is 21258751. The reversal of 21258739 is 93785212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21258739 - 2¹¹ = 21256691 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21258698 and 21258707.

It is not an unprimeable number, because it can be changed into a prime (21258733) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23887 + ... + 24760.

It is an arithmetic number, because the mean of its divisors is an integer number (2918880).

Almost surely, 2^21258739 is an apocalyptic number.

21258739 is a deficient number, since it is larger than the sum of its proper divisors (2092301).

21258739 is a wasteful number, since it uses less digits than its factorization.

21258739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48689.

The product of its digits is 30240, while the sum is 37.

The square root of 21258739 is about 4610.7200088489. The cubic root of 21258739 is about 277.0208771034.

The spelling of 21258739 in words is "twenty-one million, two hundred fifty-eight thousand, seven hundred thirty-nine".