21001403999 has 4 divisors (see below), whose sum is σ = 21056238336. Its totient is φ = 20946569664.

The previous prime is 21001403989. The next prime is 21001404013. The reversal of 21001403999 is 99930410012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21001403999 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001403909) 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, 27416594 + ... + 27417359.

It is an arithmetic number, because the mean of its divisors is an integer number (5264059584).

Almost surely, 2^21001403999 is an apocalyptic number.

21001403999 is a deficient number, since it is larger than the sum of its proper divisors (54834337).

21001403999 is an equidigital number, since it uses as much as digits as its factorization.

21001403999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54834336.

The product of its (nonzero) digits is 17496, while the sum is 38.

The spelling of 21001403999 in words is "twenty-one billion, one million, four hundred three thousand, nine hundred ninety-nine".