21758315049 has 9 divisors (see below), whose sum is σ = 31429316503. Its totient is φ = 14505248352.

The previous prime is 21758315039. The next prime is 21758315069. The reversal of 21758315049 is 94051385712.

The square root of 21758315049 is 147507.

It is a perfect power (a square), and thus also a powerful number.

21758315049 is a `hidden beast` number, since 2 + 17 + 583 + 1 + 50 + 4 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 14922332649 + 6835982400 = 122157^2 + 82680^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 21758315049 - 2¹⁵ = 21758282281 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21758314995 and 21758315013.

It is not an unprimeable number, because it can be changed into a prime (21758315039) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 417937 + ... + 467105.

Almost surely, 2^21758315049 is an apocalyptic number.

21758315049 is the 147507-th square number.

21758315049 is the 73754-th centered octagonal number.

It is an amenable number.

21758315049 is a deficient number, since it is larger than the sum of its proper divisors (9671001454).

21758315049 is an frugal number, since it uses more digits than its factorization.

21758315049 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98344 (or 49172 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 45.

The spelling of 21758315049 in words is "twenty-one billion, seven hundred fifty-eight million, three hundred fifteen thousand, forty-nine".