21170451 has 4 divisors (see below), whose sum is σ = 28227272. Its totient is φ = 14113632.

The previous prime is 21170441. The next prime is 21170453. The reversal of 21170451 is 15407112.

It is a happy number.

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

It is not a de Polignac number, because 21170451 - 2⁷ = 21170323 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21170453) 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, 3528406 + ... + 3528411.

It is an arithmetic number, because the mean of its divisors is an integer number (7056818).

Almost surely, 2^21170451 is an apocalyptic number.

21170451 is a deficient number, since it is larger than the sum of its proper divisors (7056821).

21170451 is an equidigital number, since it uses as much as digits as its factorization.

21170451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7056820.

The product of its (nonzero) digits is 280, while the sum is 21.

The square root of 21170451 is about 4601.1358380296. The cubic root of 21170451 is about 276.6368537737.

Adding to 21170451 its reverse (15407112), we get a palindrome (36577563).

The spelling of 21170451 in words is "twenty-one million, one hundred seventy thousand, four hundred fifty-one".