21605644325257 has 8 divisors (see below), whose sum is σ = 21724749517536. Its totient is φ = 21486749011872.

The previous prime is 21605644325249. The next prime is 21605644325269. The reversal of 21605644325257 is 75252344650612.

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 21605644325257 - 2³ = 21605644325249 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21605644325207) 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, 52263268 + ... + 52675045.

It is an arithmetic number, because the mean of its divisors is an integer number (2715593689692).

Almost surely, 2^{21605644325257} is an apocalyptic number.

It is an amenable number.

21605644325257 is a deficient number, since it is larger than the sum of its proper divisors (119105192279).

21605644325257 is a wasteful number, since it uses less digits than its factorization.

21605644325257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 104939447.

The product of its (nonzero) digits is 12096000, while the sum is 52.

Adding to 21605644325257 its reverse (75252344650612), we get a palindrome (96857988975869).

The spelling of 21605644325257 in words is "twenty-one trillion, six hundred five billion, six hundred forty-four million, three hundred twenty-five thousand, two hundred fifty-seven".