19642661 has 2 divisors, whose sum is σ = 19642662. Its totient is φ = 19642660.

The previous prime is 19642643. The next prime is 19642687. The reversal of 19642661 is 16624691.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11628100 + 8014561 = 3410^2 + 2831^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19642661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19644661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9821330 + 9821331.

It is an arithmetic number, because the mean of its divisors is an integer number (9821331).

Almost surely, 2^19642661 is an apocalyptic number.

It is an amenable number.

19642661 is a deficient number, since it is larger than the sum of its proper divisors (1).

19642661 is an equidigital number, since it uses as much as digits as its factorization.

19642661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15552, while the sum is 35.

The square root of 19642661 is about 4432.0041741858. The cubic root of 19642661 is about 269.8154248341.

The spelling of 19642661 in words is "nineteen million, six hundred forty-two thousand, six hundred sixty-one".