21001323841 has 2 divisors, whose sum is σ = 21001323842. Its totient is φ = 21001323840.

The previous prime is 21001323823. The next prime is 21001323853. The reversal of 21001323841 is 14832310012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18313938241 + 2687385600 = 135329^2 + 51840^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21001323841 is a prime.

It is not a weakly prime, because it can be changed into another prime (21001323041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500661920 + 10500661921.

It is an arithmetic number, because the mean of its divisors is an integer number (10500661921).

Almost surely, 2^21001323841 is an apocalyptic number.

It is an amenable number.

21001323841 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001323841 is an equidigital number, since it uses as much as digits as its factorization.

21001323841 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 25.

Adding to 21001323841 its reverse (14832310012), we get a palindrome (35833633853).

The spelling of 21001323841 in words is "twenty-one billion, one million, three hundred twenty-three thousand, eight hundred forty-one".