21432401 has 2 divisors, whose sum is σ = 21432402. Its totient is φ = 21432400.

The previous prime is 21432373. The next prime is 21432403. The reversal of 21432401 is 10423412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20430400 + 1002001 = 4520^2 + 1001^2 .

It is a cyclic number.

It is not a de Polignac number, because 21432401 - 2²² = 17238097 is a prime.

Together with 21432403, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21432401.

It is not a weakly prime, because it can be changed into another prime (21432403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10716200 + 10716201.

It is an arithmetic number, because the mean of its divisors is an integer number (10716201).

Almost surely, 2^21432401 is an apocalyptic number.

It is an amenable number.

21432401 is a deficient number, since it is larger than the sum of its proper divisors (1).

21432401 is an equidigital number, since it uses as much as digits as its factorization.

21432401 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21432401 is about 4629.5141213739. The cubic root of 21432401 is about 277.7731574283.

Adding to 21432401 its reverse (10423412), we get a palindrome (31855813).

The spelling of 21432401 in words is "twenty-one million, four hundred thirty-two thousand, four hundred one".