21825451 has 4 divisors (see below), whose sum is σ = 22151272. Its totient is φ = 21499632.

The previous prime is 21825439. The next prime is 21825469. The reversal of 21825451 is 15452812.

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 21825451 - 2²¹ = 19728299 is a prime.

It is a super-2 number, since 2×21825451² = 952700622706802, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21825481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 162810 + ... + 162943.

It is an arithmetic number, because the mean of its divisors is an integer number (5537818).

Almost surely, 2^21825451 is an apocalyptic number.

21825451 is a deficient number, since it is larger than the sum of its proper divisors (325821).

21825451 is an equidigital number, since it uses as much as digits as its factorization.

21825451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 325820.

The product of its digits is 3200, while the sum is 28.

The square root of 21825451 is about 4671.7717195942. The cubic root of 21825451 is about 279.4609142917.

The spelling of 21825451 in words is "twenty-one million, eight hundred twenty-five thousand, four hundred fifty-one".