21987803 has 2 divisors, whose sum is σ = 21987804. Its totient is φ = 21987802.

The previous prime is 21987799. The next prime is 21987809. The reversal of 21987803 is 30878912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21987803 - 2² = 21987799 is a prime.

It is not a weakly prime, because it can be changed into another prime (21987809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10993901 + 10993902.

It is an arithmetic number, because the mean of its divisors is an integer number (10993902).

Almost surely, 2^21987803 is an apocalyptic number.

21987803 is a deficient number, since it is larger than the sum of its proper divisors (1).

21987803 is an equidigital number, since it uses as much as digits as its factorization.

21987803 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24192, while the sum is 38.

The square root of 21987803 is about 4689.1153749935. The cubic root of 21987803 is about 280.1521409571.

It can be divided in two parts, 2198 and 7803, that added together give a palindrome (10001).

The spelling of 21987803 in words is "twenty-one million, nine hundred eighty-seven thousand, eight hundred three".