21200615257 has 8 divisors (see below), whose sum is σ = 21843246600. Its totient is φ = 20563962240.

The previous prime is 21200615239. The next prime is 21200615281. The reversal of 21200615257 is 75251600212.

It can be written as a sum of positive squares in 4 ways, for example, as 706974921 + 20493640336 = 26589^2 + 143156^2 .

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 21200615257 - 2¹¹ = 21200613209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21200615857) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1487382 + ... + 1501567.

It is an arithmetic number, because the mean of its divisors is an integer number (2730405825).

Almost surely, 2^21200615257 is an apocalyptic number.

It is an amenable number.

21200615257 is a deficient number, since it is larger than the sum of its proper divisors (642631343).

21200615257 is a wasteful number, since it uses less digits than its factorization.

21200615257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2989163.

The product of its (nonzero) digits is 8400, while the sum is 31.

The spelling of 21200615257 in words is "twenty-one billion, two hundred million, six hundred fifteen thousand, two hundred fifty-seven".