19499634073921 has 27 divisors (see below), whose sum is σ = 20954160852681. Its totient is φ = 18144223203744.

The previous prime is 19499634073919. The next prime is 19499634073937. The reversal of 19499634073921 is 12937043699491.

The square root of 19499634073921 is 4415839.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 9332872250625 + 10166761823296 = 3054975^2 + 3188536^2 .

It is not a de Polignac number, because 19499634073921 - 2¹ = 19499634073919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19499634073981) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 3757876395 + ... + 3757881583.

Almost surely, 2^{19499634073921} is an apocalyptic number.

19499634073921 is the 4415839-th square number.

19499634073921 is the 2207920-th centered octagonal number.

It is an amenable number.

19499634073921 is a deficient number, since it is larger than the sum of its proper divisors (1454526778760).

19499634073921 is an frugal number, since it uses more digits than its factorization.

19499634073921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10498 (or 5249 counting only the distinct ones).

The product of its (nonzero) digits is 79361856, while the sum is 67.

The spelling of 19499634073921 in words is "nineteen trillion, four hundred ninety-nine billion, six hundred thirty-four million, seventy-three thousand, nine hundred twenty-one".