19491487 has 2 divisors, whose sum is σ = 19491488. Its totient is φ = 19491486.

The previous prime is 19491481. The next prime is 19491491. The reversal of 19491487 is 78419491.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19491487 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19491481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9745743 + 9745744.

It is an arithmetic number, because the mean of its divisors is an integer number (9745744).

Almost surely, 2^19491487 is an apocalyptic number.

19491487 is a deficient number, since it is larger than the sum of its proper divisors (1).

19491487 is an equidigital number, since it uses as much as digits as its factorization.

19491487 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72576, while the sum is 43.

The square root of 19491487 is about 4414.9164204999. The cubic root of 19491487 is about 269.1214562801.

The spelling of 19491487 in words is "nineteen million, four hundred ninety-one thousand, four hundred eighty-seven".