21166311652 has 24 divisors (see below), whose sum is σ = 39323460960. Its totient is φ = 9934323840.

The previous prime is 21166311643. The next prime is 21166311653. The reversal of 21166311652 is 25611366112.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is not an unprimeable number, because it can be changed into a prime (21166311653) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 384874 + ... + 436417.

It is an arithmetic number, because the mean of its divisors is an integer number (1638477540).

Almost surely, 2^21166311652 is an apocalyptic number.

It is an amenable number.

21166311652 is a deficient number, since it is larger than the sum of its proper divisors (18157149308).

21166311652 is a wasteful number, since it uses less digits than its factorization.

21166311652 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 821691 (or 821689 counting only the distinct ones).

The product of its digits is 12960, while the sum is 34.

Adding to 21166311652 its reverse (25611366112), we get a palindrome (46777677764).

The spelling of 21166311652 in words is "twenty-one billion, one hundred sixty-six million, three hundred eleven thousand, six hundred fifty-two".