21165402313 has 4 divisors (see below), whose sum is σ = 23089529808. Its totient is φ = 19241274820.

The previous prime is 21165402299. The next prime is 21165402319. The reversal of 21165402313 is 31320456112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21165402313 is a prime.

It is a super-2 number, since 2×21165402313² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21165402319) 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, 962063731 + ... + 962063752.

It is an arithmetic number, because the mean of its divisors is an integer number (5772382452).

Almost surely, 2^21165402313 is an apocalyptic number.

It is an amenable number.

21165402313 is a deficient number, since it is larger than the sum of its proper divisors (1924127495).

21165402313 is a wasteful number, since it uses less digits than its factorization.

21165402313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1924127494.

The product of its (nonzero) digits is 4320, while the sum is 28.

Adding to 21165402313 its reverse (31320456112), we get a palindrome (52485858425).

The spelling of 21165402313 in words is "twenty-one billion, one hundred sixty-five million, four hundred two thousand, three hundred thirteen".