20520612581 has 8 divisors (see below), whose sum is σ = 24471786624. Its totient is φ = 16824353040.

The previous prime is 20520612577. The next prime is 20520612583. The reversal of 20520612581 is 18521602502.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20520612581 - 2² = 20520612577 is a prime.

It is a super-2 number, since 2×20520612581² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20520612583) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 63728450 + ... + 63728771.

It is an arithmetic number, because the mean of its divisors is an integer number (3058973328).

Almost surely, 2^20520612581 is an apocalyptic number.

It is an amenable number.

20520612581 is a deficient number, since it is larger than the sum of its proper divisors (3951174043).

20520612581 is a wasteful number, since it uses less digits than its factorization.

20520612581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127457251.

The product of its (nonzero) digits is 9600, while the sum is 32.

The spelling of 20520612581 in words is "twenty billion, five hundred twenty million, six hundred twelve thousand, five hundred eighty-one".