21523266 has 32 divisors (see below), whose sum is σ = 48081600. Its totient is φ = 7136640.

The previous prime is 21523261. The next prime is 21523267. The reversal of 21523266 is 66232512.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a nialpdrome in base 9.

It is not an unprimeable number, because it can be changed into a prime (21523261) 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, 10450 + ... + 12338.

It is an arithmetic number, because the mean of its divisors is an integer number (1502550).

Almost surely, 2^21523266 is an apocalyptic number.

21523266 is an abundant number, since it is smaller than the sum of its proper divisors (26558334).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21523266 is a wasteful number, since it uses less digits than its factorization.

21523266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2111 (or 2105 counting only the distinct ones).

The product of its digits is 4320, while the sum is 27.

The square root of 21523266 is about 4639.3174066882. The cubic root of 21523266 is about 278.1651538373.

Adding to 21523266 its reverse (66232512), we get a palindrome (87755778).

The spelling of 21523266 in words is "twenty-one million, five hundred twenty-three thousand, two hundred sixty-six".