21308697173 has 4 divisors (see below), whose sum is σ = 21319337568. Its totient is φ = 21298056780.

The previous prime is 21308697167. The next prime is 21308697191. The reversal of 21308697173 is 37179680312.

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 21308697173 - 2¹⁶ = 21308631637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21308697373) 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, 5317193 + ... + 5321198.

It is an arithmetic number, because the mean of its divisors is an integer number (5329834392).

Almost surely, 2^21308697173 is an apocalyptic number.

It is an amenable number.

21308697173 is a deficient number, since it is larger than the sum of its proper divisors (10640395).

21308697173 is a wasteful number, since it uses less digits than its factorization.

21308697173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10640394.

The product of its (nonzero) digits is 381024, while the sum is 47.

The spelling of 21308697173 in words is "twenty-one billion, three hundred eight million, six hundred ninety-seven thousand, one hundred seventy-three".