21376403 has 2 divisors, whose sum is σ = 21376404. Its totient is φ = 21376402.

The previous prime is 21376357. The next prime is 21376409. The reversal of 21376403 is 30467312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21376403 - 2⁶ = 21376339 is a prime.

It is not a weakly prime, because it can be changed into another prime (21376409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10688201 + 10688202.

It is an arithmetic number, because the mean of its divisors is an integer number (10688202).

Almost surely, 2^21376403 is an apocalyptic number.

21376403 is a deficient number, since it is larger than the sum of its proper divisors (1).

21376403 is an equidigital number, since it uses as much as digits as its factorization.

21376403 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3024, while the sum is 26.

The square root of 21376403 is about 4623.4622308396. The cubic root of 21376403 is about 277.5310270207.

Subtracting 21376403 from its reverse (30467312), we obtain a palindrome (9090909).

The spelling of 21376403 in words is "twenty-one million, three hundred seventy-six thousand, four hundred three".