21356973193 has 4 divisors (see below), whose sum is σ = 21365660880. Its totient is φ = 21348285508.

The previous prime is 21356973139. The next prime is 21356973229. The reversal of 21356973193 is 39137965312.

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 a cyclic number.

It is not a de Polignac number, because 21356973193 - 2²¹ = 21354876041 is a prime.

It is a super-2 number, since 2×21356973193² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21356973793) 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, 4340155 + ... + 4345072.

It is an arithmetic number, because the mean of its divisors is an integer number (5341415220).

Almost surely, 2^21356973193 is an apocalyptic number.

It is an amenable number.

21356973193 is a deficient number, since it is larger than the sum of its proper divisors (8687687).

21356973193 is an equidigital number, since it uses as much as digits as its factorization.

21356973193 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8687686.

The product of its digits is 918540, while the sum is 49.

The spelling of 21356973193 in words is "twenty-one billion, three hundred fifty-six million, nine hundred seventy-three thousand, one hundred ninety-three".