19956491 has 2 divisors, whose sum is σ = 19956492. Its totient is φ = 19956490.

The previous prime is 19956481. The next prime is 19956499. The reversal of 19956491 is 19465991.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19956491 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (19956499) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9978245 + 9978246.

It is an arithmetic number, because the mean of its divisors is an integer number (9978246).

Almost surely, 2^19956491 is an apocalyptic number.

19956491 is a deficient number, since it is larger than the sum of its proper divisors (1).

19956491 is an equidigital number, since it uses as much as digits as its factorization.

19956491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 87480, while the sum is 44.

The square root of 19956491 is about 4467.2688524422. The cubic root of 19956491 is about 271.2447827576.

The spelling of 19956491 in words is "nineteen million, nine hundred fifty-six thousand, four hundred ninety-one".