21990003 has 16 divisors (see below), whose sum is σ = 34010880. Its totient is φ = 12377376.

The previous prime is 21989999. The next prime is 21990013. The reversal of 21990003 is 30009912.

It is a happy number.

It is not a de Polignac number, because 21990003 - 2² = 21989999 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21990013) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6408 + ... + 9221.

It is an arithmetic number, because the mean of its divisors is an integer number (2125680).

Almost surely, 2^21990003 is an apocalyptic number.

21990003 is a deficient number, since it is larger than the sum of its proper divisors (12020877).

21990003 is a wasteful number, since it uses less digits than its factorization.

21990003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15706.

The product of its (nonzero) digits is 486, while the sum is 24.

The square root of 21990003 is about 4689.3499549511. The cubic root of 21990003 is about 280.1614842303.

Adding to 21990003 its reverse (30009912), we get a palindrome (51999915).

The spelling of 21990003 in words is "twenty-one million, nine hundred ninety thousand, three".