20505953601 has 45 divisors (see below), whose sum is σ = 35649234291. Its totient is φ = 11712532608.

The previous prime is 20505953497. The next prime is 20505953609. The reversal of 20505953601 is 10635950502.

The square root of 20505953601 is 143199.

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

20505953601 is a `hidden beast` number, since 2 + 0 + 5 + 0 + 595 + 3 + 60 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 18261468225 + 2244485376 = 135135^2 + 47376^2 .

It is not a de Polignac number, because 20505953601 - 2¹⁹ = 20505429313 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20505953609) by changing a digit.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 9020401 + ... + 9022673.

Almost surely, 2^20505953601 is an apocalyptic number.

20505953601 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

20505953601 is the 143199-th square number.

20505953601 is the 71600-th centered octagonal number.

It is an amenable number.

20505953601 is a deficient number, since it is larger than the sum of its proper divisors (15143280690).

20505953601 is an frugal number, since it uses more digits than its factorization.

20505953601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4572 (or 2283 counting only the distinct ones).

The product of its (nonzero) digits is 40500, while the sum is 36.

Multiplying 20505953601 by its sum of digits (36), we get a square (738214329636 = 859194²).

The spelling of 20505953601 in words is "twenty billion, five hundred five million, nine hundred fifty-three thousand, six hundred one".