21124661 has 2 divisors, whose sum is σ = 21124662. Its totient is φ = 21124660.

The previous prime is 21124657. The next prime is 21124681. The reversal of 21124661 is 16642112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10923025 + 10201636 = 3305^2 + 3194^2 .

It is a cyclic number.

It is not a de Polignac number, because 21124661 - 2² = 21124657 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21124601) 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 as a sum of consecutive naturals, namely, 10562330 + 10562331.

It is an arithmetic number, because the mean of its divisors is an integer number (10562331).

Almost surely, 2^21124661 is an apocalyptic number.

It is an amenable number.

21124661 is a deficient number, since it is larger than the sum of its proper divisors (1).

21124661 is an equidigital number, since it uses as much as digits as its factorization.

21124661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 576, while the sum is 23.

The square root of 21124661 is about 4596.1571992263. The cubic root of 21124661 is about 276.4372619741.

Adding to 21124661 its reverse (16642112), we get a palindrome (37766773).

The spelling of 21124661 in words is "twenty-one million, one hundred twenty-four thousand, six hundred sixty-one".