21013312331 has 4 divisors (see below), whose sum is σ = 22923613464. Its totient is φ = 19103011200.

The previous prime is 21013312303. The next prime is 21013312339. The reversal of 21013312331 is 13321331012.

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 21013312331 - 2²² = 21009118027 is a prime.

It is a super-4 number, since 4×21013312331⁴ (a number of 42 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21013312339) 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, 955150550 + ... + 955150571.

It is an arithmetic number, because the mean of its divisors is an integer number (5730903366).

Almost surely, 2^21013312331 is an apocalyptic number.

21013312331 is a deficient number, since it is larger than the sum of its proper divisors (1910301133).

21013312331 is a wasteful number, since it uses less digits than its factorization.

21013312331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1910301132.

The product of its (nonzero) digits is 324, while the sum is 20.

Adding to 21013312331 its reverse (13321331012), we get a palindrome (34334643343).

The spelling of 21013312331 in words is "twenty-one billion, thirteen million, three hundred twelve thousand, three hundred thirty-one".