21175719749 has 2 divisors, whose sum is σ = 21175719750. Its totient is φ = 21175719748.

The previous prime is 21175719731. The next prime is 21175719781. The reversal of 21175719749 is 94791757112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19305157249 + 1870562500 = 138943^2 + 43250^2 .

It is a cyclic number.

It is not a de Polignac number, because 21175719749 - 2²⁰ = 21174671173 is a prime.

It is a super-2 number, since 2×21175719749² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21175719749.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21175719709) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10587859874 + 10587859875.

It is an arithmetic number, because the mean of its divisors is an integer number (10587859875).

Almost surely, 2^21175719749 is an apocalyptic number.

It is an amenable number.

21175719749 is a deficient number, since it is larger than the sum of its proper divisors (1).

21175719749 is an equidigital number, since it uses as much as digits as its factorization.

21175719749 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1111320, while the sum is 53.

The spelling of 21175719749 in words is "twenty-one billion, one hundred seventy-five million, seven hundred nineteen thousand, seven hundred forty-nine".