21642003 has 24 divisors (see below), whose sum is σ = 34003008. Its totient is φ = 13208832.

The previous prime is 21641993. The next prime is 21642013. The reversal of 21642003 is 30024612.

It is a happy number.

21642003 is a `hidden beast` number, since 21 + 642 + 0 + 0 + 3 = 666.

It is an interprime number because it is at equal distance from previous prime (21641993) and next prime (21642013).

It is not a de Polignac number, because 21642003 - 2⁸ = 21641747 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21642013) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3750 + ... + 7572.

It is an arithmetic number, because the mean of its divisors is an integer number (1416792).

Almost surely, 2^21642003 is an apocalyptic number.

21642003 is a deficient number, since it is larger than the sum of its proper divisors (12361005).

21642003 is a wasteful number, since it uses less digits than its factorization.

21642003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3883 (or 3880 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 21642003 is about 4652.0966241040. The cubic root of 21642003 is about 278.6757322572.

Adding to 21642003 its reverse (30024612), we get a palindrome (51666615).

The spelling of 21642003 in words is "twenty-one million, six hundred forty-two thousand, three".