19948991 has 2 divisors, whose sum is σ = 19948992. Its totient is φ = 19948990.

The previous prime is 19948979. The next prime is 19948997. The reversal of 19948991 is 19984991.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19948991 - 2⁶ = 19948927 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19948997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9974495 + 9974496.

It is an arithmetic number, because the mean of its divisors is an integer number (9974496).

Almost surely, 2^19948991 is an apocalyptic number.

19948991 is a deficient number, since it is larger than the sum of its proper divisors (1).

19948991 is an equidigital number, since it uses as much as digits as its factorization.

19948991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 209952, while the sum is 50.

The square root of 19948991 is about 4466.4293344908. The cubic root of 19948991 is about 271.2107989815.

The spelling of 19948991 in words is "nineteen million, nine hundred forty-eight thousand, nine hundred ninety-one".