19887521065 has 16 divisors (see below), whose sum is σ = 25138854720. Its totient is φ = 15061982400.

The previous prime is 19887521063. The next prime is 19887521089. The reversal of 19887521065 is 56012578891.

It is not a de Polignac number, because 19887521065 - 2¹ = 19887521063 is a prime.

It is a super-2 number, since 2×19887521065² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (19887521063) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62215 + ... + 208915.

It is an arithmetic number, because the mean of its divisors is an integer number (1571178420).

Almost surely, 2^19887521065 is an apocalyptic number.

It is an amenable number.

19887521065 is a deficient number, since it is larger than the sum of its proper divisors (5251333655).

19887521065 is a wasteful number, since it uses less digits than its factorization.

19887521065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148152.

The product of its (nonzero) digits is 1209600, while the sum is 52.

The spelling of 19887521065 in words is "nineteen billion, eight hundred eighty-seven million, five hundred twenty-one thousand, sixty-five".