21253101221643 has 16 divisors (see below), whose sum is σ = 29318194394400. Its totient is φ = 13678490165760.

The previous prime is 21253101221629. The next prime is 21253101221711. The reversal of 21253101221643 is 34612210135212.

It is not a de Polignac number, because 21253101221643 - 2¹⁶ = 21253101156107 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21253101221843) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14165128 + ... + 15593493.

It is an arithmetic number, because the mean of its divisors is an integer number (1832387149650).

Almost surely, 2^{21253101221643} is an apocalyptic number.

21253101221643 is a deficient number, since it is larger than the sum of its proper divisors (8065093172757).

21253101221643 is a wasteful number, since it uses less digits than its factorization.

21253101221643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29766862.

The product of its (nonzero) digits is 17280, while the sum is 33.

Adding to 21253101221643 its reverse (34612210135212), we get a palindrome (55865311356855).

The spelling of 21253101221643 in words is "twenty-one trillion, two hundred fifty-three billion, one hundred one million, two hundred twenty-one thousand, six hundred forty-three".