21026110645 has 4 divisors (see below), whose sum is σ = 25231332780. Its totient is φ = 16820888512.

The previous prime is 21026110643. The next prime is 21026110667. The reversal of 21026110645 is 54601162012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7129944721 + 13896165924 = 84439^2 + 117882^2 .

It is a cyclic number.

It is not a de Polignac number, because 21026110645 - 2¹ = 21026110643 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21026110643) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2102611060 + ... + 2102611069.

It is an arithmetic number, because the mean of its divisors is an integer number (6307833195).

Almost surely, 2^21026110645 is an apocalyptic number.

It is an amenable number.

21026110645 is a deficient number, since it is larger than the sum of its proper divisors (4205222135).

21026110645 is an equidigital number, since it uses as much as digits as its factorization.

21026110645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4205222134.

The product of its (nonzero) digits is 2880, while the sum is 28.

Adding to 21026110645 its reverse (54601162012), we get a palindrome (75627272657).

The spelling of 21026110645 in words is "twenty-one billion, twenty-six million, one hundred ten thousand, six hundred forty-five".