21150121 has 2 divisors, whose sum is σ = 21150122. Its totient is φ = 21150120.

The previous prime is 21150113. The next prime is 21150139. The reversal of 21150121 is 12105112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20602521 + 547600 = 4539^2 + 740^2 .

It is a cyclic number.

It is not a de Polignac number, because 21150121 - 2³ = 21150113 is a prime.

It is not a weakly prime, because it can be changed into another prime (21150191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10575060 + 10575061.

It is an arithmetic number, because the mean of its divisors is an integer number (10575061).

Almost surely, 2^21150121 is an apocalyptic number.

It is an amenable number.

21150121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21150121 is an equidigital number, since it uses as much as digits as its factorization.

21150121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20, while the sum is 13.

The square root of 21150121 is about 4598.9260702908. The cubic root of 21150121 is about 276.5482738871.

Adding to 21150121 its reverse (12105112), we get a palindrome (33255233).

The spelling of 21150121 in words is "twenty-one million, one hundred fifty thousand, one hundred twenty-one".