21310313661 has 96 divisors (see below), whose sum is σ = 38922024960. Its totient is φ = 10937089152.

The previous prime is 21310313659. The next prime is 21310313701. The reversal of 21310313661 is 16631301312.

It is not a de Polignac number, because 21310313661 - 2¹ = 21310313659 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21310313621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4552120 + ... + 4556798.

It is an arithmetic number, because the mean of its divisors is an integer number (405437760).

Almost surely, 2^21310313661 is an apocalyptic number.

21310313661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21310313661 is a deficient number, since it is larger than the sum of its proper divisors (17611711299).

21310313661 is a wasteful number, since it uses less digits than its factorization.

21310313661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4855 (or 4852 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 27.

Adding to 21310313661 its reverse (16631301312), we get a palindrome (37941614973).

It can be divided in two parts, 21310 and 313661, that added together give a triangular number (334971 = T₈₁₈).

The spelling of 21310313661 in words is "twenty-one billion, three hundred ten million, three hundred thirteen thousand, six hundred sixty-one".