21145403 has 2 divisors, whose sum is σ = 21145404. Its totient is φ = 21145402.

The previous prime is 21145393. The next prime is 21145409. The reversal of 21145403 is 30454112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21145403 - 2¹⁶ = 21079867 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21145409) 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, 10572701 + 10572702.

It is an arithmetic number, because the mean of its divisors is an integer number (10572702).

Almost surely, 2^21145403 is an apocalyptic number.

21145403 is a deficient number, since it is larger than the sum of its proper divisors (1).

21145403 is an equidigital number, since it uses as much as digits as its factorization.

21145403 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 21145403 is about 4598.4130958408. The cubic root of 21145403 is about 276.5277089647.

Adding to 21145403 its reverse (30454112), we get a palindrome (51599515).

The spelling of 21145403 in words is "twenty-one million, one hundred forty-five thousand, four hundred three".