21355113531 has 8 divisors (see below), whose sum is σ = 29711462400. Its totient is φ = 13617753512.

The previous prime is 21355113529. The next prime is 21355113541. The reversal of 21355113531 is 13531155312.

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 21355113531 - 2¹ = 21355113529 is a prime.

It is a super-2 number, since 2×21355113531² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21355113541) 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, 154747131 + ... + 154747268.

It is an arithmetic number, because the mean of its divisors is an integer number (3713932800).

Almost surely, 2^21355113531 is an apocalyptic number.

21355113531 is a deficient number, since it is larger than the sum of its proper divisors (8356348869).

21355113531 is a wasteful number, since it uses less digits than its factorization.

21355113531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 309494425.

The product of its digits is 6750, while the sum is 30.

Adding to 21355113531 its reverse (13531155312), we get a palindrome (34886268843).

The spelling of 21355113531 in words is "twenty-one billion, three hundred fifty-five million, one hundred thirteen thousand, five hundred thirty-one".