21513013331 has 4 divisors (see below), whose sum is σ = 21513769464. Its totient is φ = 21512257200.

The previous prime is 21513013309. The next prime is 21513013343. The reversal of 21513013331 is 13331031512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21513013331 - 2¹⁰ = 21513012307 is a prime.

It is a super-2 number, since 2×21513013331² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21513013297 and 21513013306.

It is not an unprimeable number, because it can be changed into a prime (21513013381) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 333650 + ... + 392871.

It is an arithmetic number, because the mean of its divisors is an integer number (5378442366).

Almost surely, 2^21513013331 is an apocalyptic number.

21513013331 is a deficient number, since it is larger than the sum of its proper divisors (756133).

21513013331 is an equidigital number, since it uses as much as digits as its factorization.

21513013331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 756132.

The product of its (nonzero) digits is 810, while the sum is 23.

Adding to 21513013331 its reverse (13331031512), we get a palindrome (34844044843).

The spelling of 21513013331 in words is "twenty-one billion, five hundred thirteen million, thirteen thousand, three hundred thirty-one".