21125161 has 2 divisors, whose sum is σ = 21125162. Its totient is φ = 21125160.

The previous prime is 21125123. The next prime is 21125177. The reversal of 21125161 is 16152112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15093225 + 6031936 = 3885^2 + 2456^2 .

It is a cyclic number.

It is not a de Polignac number, because 21125161 - 2¹³ = 21116969 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21125761) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10562580 + 10562581.

It is an arithmetic number, because the mean of its divisors is an integer number (10562581).

Almost surely, 2^21125161 is an apocalyptic number.

It is an amenable number.

21125161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21125161 is an equidigital number, since it uses as much as digits as its factorization.

21125161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120, while the sum is 19.

The square root of 21125161 is about 4596.2115921702. The cubic root of 21125161 is about 276.4394429565.

Adding to 21125161 its reverse (16152112), we get a palindrome (37277273).

The spelling of 21125161 in words is "twenty-one million, one hundred twenty-five thousand, one hundred sixty-one".