21751575349 has 12 divisors (see below), whose sum is σ = 25307289324. Its totient is φ = 18640938624.

The previous prime is 21751575337. The next prime is 21751575353. The reversal of 21751575349 is 94357515712.

It can be written as a sum of positive squares in 2 ways, for example, as 5716418449 + 16035156900 = 75607^2 + 126630^2 .

It is not a de Polignac number, because 21751575349 - 2⁵ = 21751575317 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21751575049) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 267837 + ... + 339469.

It is an arithmetic number, because the mean of its divisors is an integer number (2108940777).

Almost surely, 2^21751575349 is an apocalyptic number.

It is an amenable number.

21751575349 is a deficient number, since it is larger than the sum of its proper divisors (3555713975).

21751575349 is an equidigital number, since it uses as much as digits as its factorization.

21751575349 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77844 (or 77837 counting only the distinct ones).

The product of its digits is 1323000, while the sum is 49.

The spelling of 21751575349 in words is "twenty-one billion, seven hundred fifty-one million, five hundred seventy-five thousand, three hundred forty-nine".