21577745385 has 32 divisors (see below), whose sum is σ = 43840500480. Its totient is φ = 9864111744.

The previous prime is 21577745377. The next prime is 21577745459. The reversal of 21577745385 is 58354777512.

21577745385 is a `hidden beast` number, since 2 + 157 + 77 + 45 + 385 = 666.

It is not a de Polignac number, because 21577745385 - 2³ = 21577745377 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11415852 + ... + 11417741.

It is an arithmetic number, because the mean of its divisors is an integer number (1370015640).

Almost surely, 2^21577745385 is an apocalyptic number.

It is an amenable number.

21577745385 is an abundant number, since it is smaller than the sum of its proper divisors (22262755095).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21577745385 is a wasteful number, since it uses less digits than its factorization.

21577745385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22833614 (or 22833608 counting only the distinct ones).

The product of its digits is 8232000, while the sum is 54.

It can be divided in two parts, 215777 and 45385, that added together give a palindrome (261162).

The spelling of 21577745385 in words is "twenty-one billion, five hundred seventy-seven million, seven hundred forty-five thousand, three hundred eighty-five".