19981355942601 has 27 divisors (see below), whose sum is σ = 29164470637653. Its totient is φ = 13182716805120.

The previous prime is 19981355942599. The next prime is 19981355942617. The reversal of 19981355942601 is 10624955318991.

The square root of 19981355942601 is 4470051.

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

19981355942601 is a `hidden beast` number, since 1 + 9 + 9 + 8 + 1 + 35 + 594 + 2 + 6 + 0 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1027314009225 + 18954041933376 = 1013565^2 + 4353624^2 .

It is not a de Polignac number, because 19981355942601 - 2¹ = 19981355942599 is a prime.

It is not an unprimeable number, because it can be changed into a prime (19981355949601) 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, 1300777161 + ... + 1300792521.

Almost surely, 2^{19981355942601} is an apocalyptic number.

19981355942601 is the 4470051-st square number.

19981355942601 is the 2235026-th centered octagonal number.

It is an amenable number.

19981355942601 is a deficient number, since it is larger than the sum of its proper divisors (9183114695052).

19981355942601 is an frugal number, since it uses more digits than its factorization.

19981355942601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30922 (or 15461 counting only the distinct ones).

The product of its (nonzero) digits is 20995200, while the sum is 63.

The spelling of 19981355942601 in words is "nineteen trillion, nine hundred eighty-one billion, three hundred fifty-five million, nine hundred forty-two thousand, six hundred one".