21109401 has 12 divisors (see below), whose sum is σ = 30558528. Its totient is φ = 14041944.

The previous prime is 21109397. The next prime is 21109409. The reversal of 21109401 is 10490112.

It is not a de Polignac number, because 21109401 - 2² = 21109397 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21109409) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2196 + ... + 6858.

It is an arithmetic number, because the mean of its divisors is an integer number (2546544).

Almost surely, 2^21109401 is an apocalyptic number.

It is an amenable number.

21109401 is a deficient number, since it is larger than the sum of its proper divisors (9449127).

21109401 is a wasteful number, since it uses less digits than its factorization.

21109401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5172 (or 5169 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 21109401 is about 4594.4968168451. The cubic root of 21109401 is about 276.3706818320.

Adding to 21109401 its reverse (10490112), we get a palindrome (31599513).

It can be divided in two parts, 2110 and 9401, that added together give a palindrome (11511).

The spelling of 21109401 in words is "twenty-one million, one hundred nine thousand, four hundred one".