21621263336145 has 72 divisors (see below), whose sum is σ = 41260340190888. Its totient is φ = 10466044807680.

The previous prime is 21621263336089. The next prime is 21621263336177. The reversal of 21621263336145 is 54163336212612.

21621263336145 is a `hidden beast` number, since 2 + 1 + 6 + 2 + 1 + 2 + 633 + 3 + 6 + 1 + 4 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 5542504704 + 21615720831441 = 74448^2 + 4649271^2 .

It is not a de Polignac number, because 21621263336145 - 2²² = 21621259141841 is a prime.

It is a super-2 number, since 2×21621263336145² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 21621263336145.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 141699 + ... + 6577431.

It is an arithmetic number, because the mean of its divisors is an integer number (573060280429).

Almost surely, 2^{21621263336145} is an apocalyptic number.

It is an amenable number.

21621263336145 is a deficient number, since it is larger than the sum of its proper divisors (19639076854743).

21621263336145 is a wasteful number, since it uses less digits than its factorization.

21621263336145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6436383 (or 6436369 counting only the distinct ones).

The product of its digits is 933120, while the sum is 45.

Adding to 21621263336145 its reverse (54163336212612), we get a palindrome (75784599548757).

The spelling of 21621263336145 in words is "twenty-one trillion, six hundred twenty-one billion, two hundred sixty-three million, three hundred thirty-six thousand, one hundred forty-five".