21920201 has 4 divisors (see below), whose sum is σ = 22676100. Its totient is φ = 21164304.

The previous prime is 21920179. The next prime is 21920203. The reversal of 21920201 is 10202912.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10394176 + 11526025 = 3224^2 + 3395^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21920201 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21920201.

It is not an unprimeable number, because it can be changed into a prime (21920203) 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, 377906 + ... + 377963.

It is an arithmetic number, because the mean of its divisors is an integer number (5669025).

Almost surely, 2^21920201 is an apocalyptic number.

It is an amenable number.

21920201 is a deficient number, since it is larger than the sum of its proper divisors (755899).

21920201 is an equidigital number, since it uses as much as digits as its factorization.

21920201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 755898.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21920201 is about 4681.9014299748. The cubic root of 21920201 is about 279.8647348354.

The spelling of 21920201 in words is "twenty-one million, nine hundred twenty thousand, two hundred one".