21403505237 has 2 divisors, whose sum is σ = 21403505238. Its totient is φ = 21403505236.

The previous prime is 21403505219. The next prime is 21403505269. The reversal of 21403505237 is 73250530412.

It is an a-pointer prime, because the next prime (21403505269) can be obtained adding 21403505237 to its sum of digits (32).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18628428196 + 2775077041 = 136486^2 + 52679^2 .

It is a cyclic number.

It is not a de Polignac number, because 21403505237 - 2³⁰ = 20329763413 is a prime.

It is a super-2 number, since 2×21403505237² (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 (21403501237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10701752618 + 10701752619.

It is an arithmetic number, because the mean of its divisors is an integer number (10701752619).

Almost surely, 2^21403505237 is an apocalyptic number.

It is an amenable number.

21403505237 is a deficient number, since it is larger than the sum of its proper divisors (1).

21403505237 is an equidigital number, since it uses as much as digits as its factorization.

21403505237 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 25200, while the sum is 32.

The spelling of 21403505237 in words is "twenty-one billion, four hundred three million, five hundred five thousand, two hundred thirty-seven".