21415253791 has 4 divisors (see below), whose sum is σ = 21994044472. Its totient is φ = 20836463112.

The previous prime is 21415253773. The next prime is 21415253819. The reversal of 21415253791 is 19735251412.

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

It is a cyclic number.

It is not a de Polignac number, because 21415253791 - 2¹¹ = 21415251743 is a prime.

It is a super-3 number, since 3×21415253791³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21415253711) 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, 289395285 + ... + 289395358.

It is an arithmetic number, because the mean of its divisors is an integer number (5498511118).

Almost surely, 2^21415253791 is an apocalyptic number.

21415253791 is a deficient number, since it is larger than the sum of its proper divisors (578790681).

21415253791 is an equidigital number, since it uses as much as digits as its factorization.

21415253791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 578790680.

The product of its digits is 75600, while the sum is 40.

The spelling of 21415253791 in words is "twenty-one billion, four hundred fifteen million, two hundred fifty-three thousand, seven hundred ninety-one".