21720246351 has 8 divisors (see below), whose sum is σ = 30219473280. Its totient is φ = 13850591832.

The previous prime is 21720246343. The next prime is 21720246389. The reversal of 21720246351 is 15364202712.

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

It is not a de Polignac number, because 21720246351 - 2³ = 21720246343 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21720246311) 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, 157393021 + ... + 157393158.

It is an arithmetic number, because the mean of its divisors is an integer number (3777434160).

Almost surely, 2^21720246351 is an apocalyptic number.

21720246351 is a deficient number, since it is larger than the sum of its proper divisors (8499226929).

21720246351 is a wasteful number, since it uses less digits than its factorization.

21720246351 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 314786205.

The product of its (nonzero) digits is 20160, while the sum is 33.

The spelling of 21720246351 in words is "twenty-one billion, seven hundred twenty million, two hundred forty-six thousand, three hundred fifty-one".