19987769 has 2 divisors, whose sum is σ = 19987770. Its totient is φ = 19987768.

The previous prime is 19987741. The next prime is 19987789. The reversal of 19987769 is 96778991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13227769 + 6760000 = 3637^2 + 2600^2 .

It is a cyclic number.

It is not a de Polignac number, because 19987769 - 2¹² = 19983673 is a prime.

It is a super-2 number, since 2×19987769² = 799021819194722, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (19987789) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9993884 + 9993885.

It is an arithmetic number, because the mean of its divisors is an integer number (9993885).

Almost surely, 2^19987769 is an apocalyptic number.

It is an amenable number.

19987769 is a deficient number, since it is larger than the sum of its proper divisors (1).

19987769 is an equidigital number, since it uses as much as digits as its factorization.

19987769 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1714608, while the sum is 56.

The square root of 19987769 is about 4470.7682784953. The cubic root of 19987769 is about 271.3864169728.

The spelling of 19987769 in words is "nineteen million, nine hundred eighty-seven thousand, seven hundred sixty-nine".