21535243155 has 12 divisors (see below), whose sum is σ = 37327754880. Its totient is φ = 11485462992.

The previous prime is 21535243151. The next prime is 21535243189. The reversal of 21535243155 is 55134253512.

21535243155 is a `hidden beast` number, since 2 + 1 + 53 + 524 + 31 + 55 = 666.

It is not a de Polignac number, because 21535243155 - 2² = 21535243151 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21535243151) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 239280435 + ... + 239280524.

It is an arithmetic number, because the mean of its divisors is an integer number (3110646240).

Almost surely, 2^21535243155 is an apocalyptic number.

21535243155 is a deficient number, since it is larger than the sum of its proper divisors (15792511725).

21535243155 is a wasteful number, since it uses less digits than its factorization.

21535243155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 478560970 (or 478560967 counting only the distinct ones).

The product of its digits is 90000, while the sum is 36.

Adding to 21535243155 its reverse (55134253512), we get a palindrome (76669496667).

The spelling of 21535243155 in words is "twenty-one billion, five hundred thirty-five million, two hundred forty-three thousand, one hundred fifty-five".