21021043156 has 12 divisors (see below), whose sum is σ = 36788408692. Its totient is φ = 10510069248.

The previous prime is 21021043151. The next prime is 21021043157. The reversal of 21021043156 is 65134012012.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20942720656 + 78322500 = 144716^2 + 8850^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21021043156.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021043151) 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 3 ways as a sum of consecutive naturals, for example, 5236 + ... + 205108.

Almost surely, 2^21021043156 is an apocalyptic number.

It is an amenable number.

21021043156 is a deficient number, since it is larger than the sum of its proper divisors (15767365536).

21021043156 is a wasteful number, since it uses less digits than its factorization.

21021043156 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 226170 (or 226168 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

Adding to 21021043156 its reverse (65134012012), we get a palindrome (86155055168).

The spelling of 21021043156 in words is "twenty-one billion, twenty-one million, forty-three thousand, one hundred fifty-six".