21903601 has 4 divisors (see below), whose sum is σ = 21915252. Its totient is φ = 21891952.

The previous prime is 21903587. The next prime is 21903643. The reversal of 21903601 is 10630912.

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 can be written as a sum of positive squares in 2 ways, for example, as 2719201 + 19184400 = 1649^2 + 4380^2 .

It is a cyclic number.

It is not a de Polignac number, because 21903601 - 2⁵ = 21903569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21903901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2290 + ... + 7003.

It is an arithmetic number, because the mean of its divisors is an integer number (5478813).

Almost surely, 2^21903601 is an apocalyptic number.

It is an amenable number.

21903601 is a deficient number, since it is larger than the sum of its proper divisors (11651).

21903601 is an equidigital number, since it uses as much as digits as its factorization.

21903601 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11650.

The product of its (nonzero) digits is 324, while the sum is 22.

The square root of 21903601 is about 4680.1283102069. The cubic root of 21903601 is about 279.7940705225.

The spelling of 21903601 in words is "twenty-one million, nine hundred three thousand, six hundred one".