21247395917 has 8 divisors (see below), whose sum is σ = 23231305440. Its totient is φ = 19272207760.

The previous prime is 21247395899. The next prime is 21247395937. The reversal of 21247395917 is 71959374212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21247395917 - 2⁶ = 21247395853 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 (21247395937) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2175242 + ... + 2184987.

It is an arithmetic number, because the mean of its divisors is an integer number (2903913180).

Almost surely, 2^21247395917 is an apocalyptic number.

It is an amenable number.

21247395917 is a deficient number, since it is larger than the sum of its proper divisors (1983909523).

21247395917 is a wasteful number, since it uses less digits than its factorization.

21247395917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4360683.

The product of its digits is 952560, while the sum is 50.

The spelling of 21247395917 in words is "twenty-one billion, two hundred forty-seven million, three hundred ninety-five thousand, nine hundred seventeen".