21516343385 has 8 divisors (see below), whose sum is σ = 25820400456. Its totient is φ = 17212549120.

The previous prime is 21516343357. The next prime is 21516343391. The reversal of 21516343385 is 58334361512.

It can be written as a sum of positive squares in 4 ways, for example, as 440896 + 21515902489 = 664^2 + 146683^2 .

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

It is not a de Polignac number, because 21516343385 - 2⁸ = 21516343129 is a prime.

It is a super-2 number, since 2×21516343385² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 275747 + ... + 345063.

It is an arithmetic number, because the mean of its divisors is an integer number (3227550057).

Almost surely, 2^21516343385 is an apocalyptic number.

It is an amenable number.

21516343385 is a deficient number, since it is larger than the sum of its proper divisors (4304057071).

21516343385 is an equidigital number, since it uses as much as digits as its factorization.

21516343385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131403.

The product of its digits is 259200, while the sum is 41.

The spelling of 21516343385 in words is "twenty-one billion, five hundred sixteen million, three hundred forty-three thousand, three hundred eighty-five".