19661497 has 2 divisors, whose sum is σ = 19661498. Its totient is φ = 19661496.

The previous prime is 19661491. The next prime is 19661501. The reversal of 19661497 is 79416691.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18844281 + 817216 = 4341^2 + 904^2 .

It is an emirp because it is prime and its reverse (79416691) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19661497 is a prime.

It is not a weakly prime, because it can be changed into another prime (19661491) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9830748 + 9830749.

It is an arithmetic number, because the mean of its divisors is an integer number (9830749).

Almost surely, 2^19661497 is an apocalyptic number.

It is an amenable number.

19661497 is a deficient number, since it is larger than the sum of its proper divisors (1).

19661497 is an equidigital number, since it uses as much as digits as its factorization.

19661497 is an evil number, because the sum of its binary digits is even.

The product of its digits is 81648, while the sum is 43.

The square root of 19661497 is about 4434.1286629957. The cubic root of 19661497 is about 269.9016422717.

The spelling of 19661497 in words is "nineteen million, six hundred sixty-one thousand, four hundred ninety-seven".