21645266 has 8 divisors (see below), whose sum is σ = 32638464. Its totient is φ = 10765780.

The previous prime is 21645257. The next prime is 21645287. The reversal of 21645266 is 66254612.

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

It is a plaindrome in base 11.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27950 + ... + 28713.

It is an arithmetic number, because the mean of its divisors is an integer number (4079808).

Almost surely, 2^21645266 is an apocalyptic number.

21645266 is a deficient number, since it is larger than the sum of its proper divisors (10993198).

21645266 is a wasteful number, since it uses less digits than its factorization.

21645266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56856.

The product of its digits is 17280, while the sum is 32.

The square root of 21645266 is about 4652.4473129741. The cubic root of 21645266 is about 278.6897370179.

Adding to 21645266 its reverse (66254612), we get a palindrome (87899878).

It can be divided in two parts, 2164526 and 6, that multiplied together give a triangular number (12987156 = T₅₀₉₆).

The spelling of 21645266 in words is "twenty-one million, six hundred forty-five thousand, two hundred sixty-six".