21355581757 has 8 divisors (see below), whose sum is σ = 21512840384. Its totient is φ = 21198643488.

The previous prime is 21355581631. The next prime is 21355581769. The reversal of 21355581757 is 75718555312.

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 21355581757 - 2¹¹ = 21355579709 is a prime.

It is a super-2 number, since 2×21355581757² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21355581757.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21355581787) 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, 54553 + ... + 213745.

It is an arithmetic number, because the mean of its divisors is an integer number (2689105048).

Almost surely, 2^21355581757 is an apocalyptic number.

It is an amenable number.

21355581757 is a deficient number, since it is larger than the sum of its proper divisors (157258627).

21355581757 is a wasteful number, since it uses less digits than its factorization.

21355581757 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160179.

The product of its digits is 1470000, while the sum is 49.

The spelling of 21355581757 in words is "twenty-one billion, three hundred fifty-five million, five hundred eighty-one thousand, seven hundred fifty-seven".