21001111501 has 2 divisors, whose sum is σ = 21001111502. Its totient is φ = 21001111500.

The previous prime is 21001111477. The next prime is 21001111543. The reversal of 21001111501 is 10511110012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10831397476 + 10169714025 = 104074^2 + 100845^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001111501 - 2¹³ = 21001103309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001114501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500555750 + 10500555751.

It is an arithmetic number, because the mean of its divisors is an integer number (10500555751).

Almost surely, 2^21001111501 is an apocalyptic number.

It is an amenable number.

21001111501 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001111501 is an equidigital number, since it uses as much as digits as its factorization.

21001111501 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10, while the sum is 13.

Adding to 21001111501 its reverse (10511110012), we get a palindrome (31512221513).

The spelling of 21001111501 in words is "twenty-one billion, one million, one hundred eleven thousand, five hundred one".