21660403 has 4 divisors (see below), whose sum is σ = 21670480. Its totient is φ = 21650328.

The previous prime is 21660389. The next prime is 21660407. The reversal of 21660403 is 30406612.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21660403 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21660407) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 375 + ... + 6592.

It is an arithmetic number, because the mean of its divisors is an integer number (5417620).

Almost surely, 2^21660403 is an apocalyptic number.

21660403 is a deficient number, since it is larger than the sum of its proper divisors (10077).

21660403 is an equidigital number, since it uses as much as digits as its factorization.

21660403 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10076.

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 21660403 is about 4654.0738068922. The cubic root of 21660403 is about 278.7546864556.

The spelling of 21660403 in words is "twenty-one million, six hundred sixty thousand, four hundred three".