21453401 has 2 divisors, whose sum is σ = 21453402. Its totient is φ = 21453400.

The previous prime is 21453391. The next prime is 21453427. The reversal of 21453401 is 10435412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14055001 + 7398400 = 3749^2 + 2720^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21453401 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21453101) 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 as a sum of consecutive naturals, namely, 10726700 + 10726701.

It is an arithmetic number, because the mean of its divisors is an integer number (10726701).

Almost surely, 2^21453401 is an apocalyptic number.

It is an amenable number.

21453401 is a deficient number, since it is larger than the sum of its proper divisors (1).

21453401 is an equidigital number, since it uses as much as digits as its factorization.

21453401 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 21453401 is about 4631.7816226588. The cubic root of 21453401 is about 277.8638508316.

Adding to 21453401 its reverse (10435412), we get a palindrome (31888813).

The spelling of 21453401 in words is "twenty-one million, four hundred fifty-three thousand, four hundred one".