21126403 has 2 divisors, whose sum is σ = 21126404. Its totient is φ = 21126402.

The previous prime is 21126379. The next prime is 21126409. The reversal of 21126403 is 30462112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21126403 - 2¹³ = 21118211 is a prime.

It is not a weakly prime, because it can be changed into another prime (21126409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10563201 + 10563202.

It is an arithmetic number, because the mean of its divisors is an integer number (10563202).

Almost surely, 2^21126403 is an apocalyptic number.

21126403 is a deficient number, since it is larger than the sum of its proper divisors (1).

21126403 is an equidigital number, since it uses as much as digits as its factorization.

21126403 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 21126403 is about 4596.3467014576. The cubic root of 21126403 is about 276.4448603678. Note that the first 3 decimals are identical.

Adding to 21126403 its reverse (30462112), we get a palindrome (51588515).

It can be divided in two parts, 2112 and 6403, that added together give a triangular number (8515 = T₁₃₀).

The spelling of 21126403 in words is "twenty-one million, one hundred twenty-six thousand, four hundred three".