21258645 has 16 divisors (see below), whose sum is σ = 34098432. Its totient is φ = 11309760.

The previous prime is 21258613. The next prime is 21258649. The reversal of 21258645 is 54685212.

It is not a de Polignac number, because 21258645 - 2⁵ = 21258613 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21258649) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5415 + ... + 8475.

It is an arithmetic number, because the mean of its divisors is an integer number (2131152).

Almost surely, 2^21258645 is an apocalyptic number.

It is an amenable number.

21258645 is a deficient number, since it is larger than the sum of its proper divisors (12839787).

21258645 is a wasteful number, since it uses less digits than its factorization.

21258645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3532.

The product of its digits is 19200, while the sum is 33.

The square root of 21258645 is about 4610.7098152020. The cubic root of 21258645 is about 277.0204688007.

The spelling of 21258645 in words is "twenty-one million, two hundred fifty-eight thousand, six hundred forty-five".