19965557 has 2 divisors, whose sum is σ = 19965558. Its totient is φ = 19965556.

The previous prime is 19965551. The next prime is 19965613. The reversal of 19965557 is 75556991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16434916 + 3530641 = 4054^2 + 1879^2 .

It is a cyclic number.

It is not a de Polignac number, because 19965557 - 2⁶ = 19965493 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (19965551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9982778 + 9982779.

It is an arithmetic number, because the mean of its divisors is an integer number (9982779).

Almost surely, 2^19965557 is an apocalyptic number.

It is an amenable number.

19965557 is a deficient number, since it is larger than the sum of its proper divisors (1).

19965557 is an equidigital number, since it uses as much as digits as its factorization.

19965557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 425250, while the sum is 47.

The square root of 19965557 is about 4468.2834511700. The cubic root of 19965557 is about 271.2858509814.

It can be divided in two parts, 199 and 65557, that added together give a palindrome (65756).

The spelling of 19965557 in words is "nineteen million, nine hundred sixty-five thousand, five hundred fifty-seven".