20197810161 has 15 divisors (see below), whose sum is σ = 30173948233. Its totient is φ = 13464354060.

The previous prime is 20197810147. The next prime is 20197810189. The reversal of 20197810161 is 16101879102.

The square root of 20197810161 is 142119.

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

It is not a de Polignac number, because 20197810161 - 2¹⁹ = 20197285873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20197810561) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 1271176 + ... + 1286966.

Almost surely, 2^20197810161 is an apocalyptic number.

20197810161 is the 142119-th square number.

20197810161 is the 71060-th centered octagonal number.

It is an amenable number.

20197810161 is a deficient number, since it is larger than the sum of its proper divisors (9976138072).

20197810161 is an frugal number, since it uses more digits than its factorization.

20197810161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31594 (or 15794 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 36.

Multiplying 20197810161 by its sum of digits (36), we get a square (727121165796 = 852714²).

The spelling of 20197810161 in words is "twenty billion, one hundred ninety-seven million, eight hundred ten thousand, one hundred sixty-one".