21221555013 has 8 divisors (see below), whose sum is σ = 31439340800. Its totient is φ = 14147703324.

The previous prime is 21221554999. The next prime is 21221555029. The reversal of 21221555013 is 31055512212.

21221555013 is a `hidden beast` number, since 2 + 1 + 2 + 2 + 155 + 501 + 3 = 666.

It is not a de Polignac number, because 21221555013 - 2¹⁴ = 21221538629 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 785983519 = 21221555013 / (2 + 1 + 2 + 2 + 1 + 5 + 5 + 5 + 0 + 1 + 3).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221545013) 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 7 ways as a sum of consecutive naturals, for example, 392991733 + ... + 392991786.

It is an arithmetic number, because the mean of its divisors is an integer number (3929917600).

Almost surely, 2^21221555013 is an apocalyptic number.

It is an amenable number.

21221555013 is a deficient number, since it is larger than the sum of its proper divisors (10217785787).

21221555013 is an equidigital number, since it uses as much as digits as its factorization.

21221555013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 785983528 (or 785983522 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 27.

The spelling of 21221555013 in words is "twenty-one billion, two hundred twenty-one million, five hundred fifty-five thousand, thirteen".