21042901 has 4 divisors (see below), whose sum is σ = 22955904. Its totient is φ = 19129900.

The previous prime is 21042883. The next prime is 21042911. The reversal of 21042901 is 10924012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21042901 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 (21042911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 956485 + ... + 956506.

It is an arithmetic number, because the mean of its divisors is an integer number (5738976).

Almost surely, 2^21042901 is an apocalyptic number.

It is an amenable number.

21042901 is a deficient number, since it is larger than the sum of its proper divisors (1913003).

21042901 is a wasteful number, since it uses less digits than its factorization.

21042901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1913002.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 21042901 is about 4587.2541895997. The cubic root of 21042901 is about 276.0801638248.

Adding to 21042901 its reverse (10924012), we get a palindrome (31966913).

It can be divided in two parts, 2104 and 2901, that added together give a palindrome (5005).

The spelling of 21042901 in words is "twenty-one million, forty-two thousand, nine hundred one".