20097528581 has 4 divisors (see below), whose sum is σ = 21643492332. Its totient is φ = 18551564832.

The previous prime is 20097528553. The next prime is 20097528587. The reversal of 20097528581 is 18582579002.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 787924900 + 19309603681 = 28070^2 + 138959^2 .

It is a cyclic number.

It is not a de Polignac number, because 20097528581 - 2²² = 20093334277 is a prime.

It is a super-2 number, since 2×20097528581² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20097528587) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 772981856 + ... + 772981881.

It is an arithmetic number, because the mean of its divisors is an integer number (5410873083).

Almost surely, 2^20097528581 is an apocalyptic number.

It is an amenable number.

20097528581 is a deficient number, since it is larger than the sum of its proper divisors (1545963751).

20097528581 is a wasteful number, since it uses less digits than its factorization.

20097528581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1545963750.

The product of its (nonzero) digits is 403200, while the sum is 47.

The spelling of 20097528581 in words is "twenty billion, ninety-seven million, five hundred twenty-eight thousand, five hundred eighty-one".