21739670197 has 4 divisors (see below), whose sum is σ = 24845337376. Its totient is φ = 18634003020.

The previous prime is 21739670191. The next prime is 21739670231. The reversal of 21739670197 is 79107693712.

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 21739670197 - 2³ = 21739670189 is a prime.

It is a super-2 number, since 2×21739670197² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21739670191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1552833579 + ... + 1552833592.

It is an arithmetic number, because the mean of its divisors is an integer number (6211334344).

Almost surely, 2^21739670197 is an apocalyptic number.

It is an amenable number.

21739670197 is a deficient number, since it is larger than the sum of its proper divisors (3105667179).

21739670197 is an equidigital number, since it uses as much as digits as its factorization.

21739670197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3105667178.

The product of its (nonzero) digits is 1000188, while the sum is 52.

The spelling of 21739670197 in words is "twenty-one billion, seven hundred thirty-nine million, six hundred seventy thousand, one hundred ninety-seven".