21147994353 has 4 divisors (see below), whose sum is σ = 28197325808. Its totient is φ = 14098662900.

The previous prime is 21147994337. The next prime is 21147994363. The reversal of 21147994353 is 35349974112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21147994353 - 2⁴ = 21147994337 is a prime.

It is the 145424-th Hogben number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21147994313) by changing a digit.

It is a nontrivial repunit in base 145423.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3524665723 + ... + 3524665728.

It is an arithmetic number, because the mean of its divisors is an integer number (7049331452).

Almost surely, 2^21147994353 is an apocalyptic number.

It is an amenable number.

21147994353 is a deficient number, since it is larger than the sum of its proper divisors (7049331455).

21147994353 is an equidigital number, since it uses as much as digits as its factorization.

21147994353 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7049331454.

The product of its digits is 816480, while the sum is 48.

The spelling of 21147994353 in words is "twenty-one billion, one hundred forty-seven million, nine hundred ninety-four thousand, three hundred fifty-three".