21630061 has 2 divisors, whose sum is σ = 21630062. Its totient is φ = 21630060.

The previous prime is 21630031. The next prime is 21630067. The reversal of 21630061 is 16003612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19527561 + 2102500 = 4419^2 + 1450^2 .

It is a cyclic number.

It is not a de Polignac number, because 21630061 - 2¹⁷ = 21498989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21630067) 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, 10815030 + 10815031.

It is an arithmetic number, because the mean of its divisors is an integer number (10815031).

Almost surely, 2^21630061 is an apocalyptic number.

It is an amenable number.

21630061 is a deficient number, since it is larger than the sum of its proper divisors (1).

21630061 is an equidigital number, since it uses as much as digits as its factorization.

21630061 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 216, while the sum is 19.

The square root of 21630061 is about 4650.8129396913. The cubic root of 21630061 is about 278.6244653158.

Adding to 21630061 its reverse (16003612), we get a palindrome (37633673).

The spelling of 21630061 in words is "twenty-one million, six hundred thirty thousand, sixty-one".