21003403261 has 2 divisors, whose sum is σ = 21003403262. Its totient is φ = 21003403260.

The previous prime is 21003403237. The next prime is 21003403273. The reversal of 21003403261 is 16230430012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11322024025 + 9681379236 = 106405^2 + 98394^2 .

It is a cyclic number.

It is not a de Polignac number, because 21003403261 - 2⁵ = 21003403229 is a prime.

It is a super-2 number, since 2×21003403261² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21003403361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501701630 + 10501701631.

It is an arithmetic number, because the mean of its divisors is an integer number (10501701631).

Almost surely, 2^21003403261 is an apocalyptic number.

It is an amenable number.

21003403261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21003403261 is an equidigital number, since it uses as much as digits as its factorization.

21003403261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 22.

Adding to 21003403261 its reverse (16230430012), we get a palindrome (37233833273).

The spelling of 21003403261 in words is "twenty-one billion, three million, four hundred three thousand, two hundred sixty-one".