21040121 has 2 divisors, whose sum is σ = 21040122. Its totient is φ = 21040120.

The previous prime is 21040111. The next prime is 21040139. The reversal of 21040121 is 12104012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14714896 + 6325225 = 3836^2 + 2515^2 .

It is a cyclic number.

It is not a de Polignac number, because 21040121 - 2⁶ = 21040057 is a prime.

It is a Chen prime.

It is a plaindrome in base 13.

It is not a weakly prime, because it can be changed into another prime (21040111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10520060 + 10520061.

It is an arithmetic number, because the mean of its divisors is an integer number (10520061).

Almost surely, 2^21040121 is an apocalyptic number.

It is an amenable number.

21040121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21040121 is an equidigital number, since it uses as much as digits as its factorization.

21040121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 21040121 is about 4586.9511660797. The cubic root of 21040121 is about 276.0680055415.

Adding to 21040121 its reverse (12104012), we get a palindrome (33144133).

The spelling of 21040121 in words is "twenty-one million, forty thousand, one hundred twenty-one".