20765537581 has 8 divisors (see below), whose sum is σ = 21437107200. Its totient is φ = 20094075120.

The previous prime is 20765537563. The next prime is 20765537591. The reversal of 20765537581 is 18573556702.

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 20765537581 - 2⁷ = 20765537453 is a prime.

It is a super-2 number, since 2×20765537581² (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 (20765537531) 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, 600675 + ... + 634303.

It is an arithmetic number, because the mean of its divisors is an integer number (2679638400).

Almost surely, 2^20765537581 is an apocalyptic number.

It is an amenable number.

20765537581 is a deficient number, since it is larger than the sum of its proper divisors (671569619).

20765537581 is a wasteful number, since it uses less digits than its factorization.

20765537581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53579.

The product of its (nonzero) digits is 1764000, while the sum is 49.

The spelling of 20765537581 in words is "twenty billion, seven hundred sixty-five million, five hundred thirty-seven thousand, five hundred eighty-one".