21420403 has 2 divisors, whose sum is σ = 21420404. Its totient is φ = 21420402.

The previous prime is 21420397. The next prime is 21420433. The reversal of 21420403 is 30402412.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21420403 is a prime.

It is not a weakly prime, because it can be changed into another prime (21420433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710201 + 10710202.

It is an arithmetic number, because the mean of its divisors is an integer number (10710202).

Almost surely, 2^21420403 is an apocalyptic number.

21420403 is a deficient number, since it is larger than the sum of its proper divisors (1).

21420403 is an equidigital number, since it uses as much as digits as its factorization.

21420403 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 21420403 is about 4628.2181236411. The cubic root of 21420403 is about 277.7213146689.

Adding to 21420403 its reverse (30402412), we get a palindrome (51822815).

Subtracting 21420403 from its reverse (30402412), we obtain a square (8982009 = 2997²).

The spelling of 21420403 in words is "twenty-one million, four hundred twenty thousand, four hundred three".