21221545260643 has 32 divisors (see below), whose sum is σ = 26137867916160. Its totient is φ = 16778436111360.

The previous prime is 21221545260637. The next prime is 21221545260697. The reversal of 21221545260643 is 34606254512212.

It is not a de Polignac number, because 21221545260643 - 2¹³ = 21221545252451 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21221545260643.

It is not an unprimeable number, because it can be changed into a prime (21221545264643) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 760151721 + ... + 760179637.

It is an arithmetic number, because the mean of its divisors is an integer number (816808372380).

Almost surely, 2^{21221545260643} is an apocalyptic number.

21221545260643 is a deficient number, since it is larger than the sum of its proper divisors (4916322655517).

21221545260643 is a wasteful number, since it uses less digits than its factorization.

21221545260643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33727.

The product of its (nonzero) digits is 691200, while the sum is 43.

Adding to 21221545260643 its reverse (34606254512212), we get a palindrome (55827799772855).

The spelling of 21221545260643 in words is "twenty-one trillion, two hundred twenty-one billion, five hundred forty-five million, two hundred sixty thousand, six hundred forty-three".