21253554 has 36 divisors (see below), whose sum is σ = 53569854. Its totient is φ = 6072192.

The previous prime is 21253543. The next prime is 21253591. The reversal of 21253554 is 45535212.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 15421329 + 5832225 = 3927^2 + 2415^2 .

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 11167 + ... + 12930.

Almost surely, 2^21253554 is an apocalyptic number.

21253554 is an abundant number, since it is smaller than the sum of its proper divisors (32316300).

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

21253554 is a wasteful number, since it uses less digits than its factorization.

21253554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24119 (or 24109 counting only the distinct ones).

The product of its digits is 6000, while the sum is 27.

The square root of 21253554 is about 4610.1576979535. The cubic root of 21253554 is about 276.9983535028.

Adding to 21253554 its reverse (45535212), we get a palindrome (66788766).

The spelling of 21253554 in words is "twenty-one million, two hundred fifty-three thousand, five hundred fifty-four".