21175764245 has 8 divisors (see below), whose sum is σ = 25412341560. Its totient is φ = 16939661760.

The previous prime is 21175764221. The next prime is 21175764251. The reversal of 21175764245 is 54246757112.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 2712118084 + 18463646161 = 52078^2 + 135881^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21175764245 - 2⁸ = 21175763989 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21175764196 and 21175764205.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11846 + ... + 206135.

It is an arithmetic number, because the mean of its divisors is an integer number (3176542695).

Almost surely, 2^21175764245 is an apocalyptic number.

It is an amenable number.

21175764245 is a deficient number, since it is larger than the sum of its proper divisors (4236577315).

21175764245 is a wasteful number, since it uses less digits than its factorization.

21175764245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 237415.

The product of its digits is 470400, while the sum is 44.

The spelling of 21175764245 in words is "twenty-one billion, one hundred seventy-five million, seven hundred sixty-four thousand, two hundred forty-five".