21758794457 has 4 divisors (see below), whose sum is σ = 21759469476. Its totient is φ = 21758119440.

The previous prime is 21758794451. The next prime is 21758794483. The reversal of 21758794457 is 75449785712.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5337909721 + 16420884736 = 73061^2 + 128144^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21758794457 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21758794396 and 21758794405.

It is not an unprimeable number, because it can be changed into a prime (21758794451) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 286598 + ... + 354479.

It is an arithmetic number, because the mean of its divisors is an integer number (5439867369).

Almost surely, 2^21758794457 is an apocalyptic number.

It is an amenable number.

21758794457 is a deficient number, since it is larger than the sum of its proper divisors (675019).

21758794457 is an equidigital number, since it uses as much as digits as its factorization.

21758794457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 675018.

The product of its digits is 19756800, while the sum is 59.

The spelling of 21758794457 in words is "twenty-one billion, seven hundred fifty-eight million, seven hundred ninety-four thousand, four hundred fifty-seven".