21452251 has 4 divisors (see below), whose sum is σ = 21511072. Its totient is φ = 21393432.

The previous prime is 21452243. The next prime is 21452269. The reversal of 21452251 is 15225412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21452251 - 2³ = 21452243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21452201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28860 + ... + 29593.

It is an arithmetic number, because the mean of its divisors is an integer number (5377768).

Almost surely, 2^21452251 is an apocalyptic number.

21452251 is a deficient number, since it is larger than the sum of its proper divisors (58821).

21452251 is an equidigital number, since it uses as much as digits as its factorization.

21452251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58820.

The product of its digits is 800, while the sum is 22.

The square root of 21452251 is about 4631.6574787003. The cubic root of 21452251 is about 277.8588858202.

Adding to 21452251 its reverse (15225412), we get a palindrome (36677663).

The spelling of 21452251 in words is "twenty-one million, four hundred fifty-two thousand, two hundred fifty-one".