21043031501 has 2 divisors, whose sum is σ = 21043031502. Its totient is φ = 21043031500.

The previous prime is 21043031491. The next prime is 21043031507. The reversal of 21043031501 is 10513034012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14622855625 + 6420175876 = 120925^2 + 80126^2 .

It is a cyclic number.

It is not a de Polignac number, because 21043031501 - 2¹⁴ = 21043015117 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21043031507) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10521515750 + 10521515751.

It is an arithmetic number, because the mean of its divisors is an integer number (10521515751).

Almost surely, 2^21043031501 is an apocalyptic number.

It is an amenable number.

21043031501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21043031501 is an equidigital number, since it uses as much as digits as its factorization.

21043031501 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 360, while the sum is 20.

Adding to 21043031501 its reverse (10513034012), we get a palindrome (31556065513).

The spelling of 21043031501 in words is "twenty-one billion, forty-three million, thirty-one thousand, five hundred one".