21727427257 has 4 divisors (see below), whose sum is σ = 22870976080. Its totient is φ = 20583878436.

The previous prime is 21727427251. The next prime is 21727427317. The reversal of 21727427257 is 75272472712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21727427257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21727427251) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 571774383 + ... + 571774420.

It is an arithmetic number, because the mean of its divisors is an integer number (5717744020).

Almost surely, 2^21727427257 is an apocalyptic number.

It is an amenable number.

21727427257 is a deficient number, since it is larger than the sum of its proper divisors (1143548823).

21727427257 is a wasteful number, since it uses less digits than its factorization.

21727427257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1143548822.

The product of its digits is 768320, while the sum is 46.

Adding to 21727427257 its reverse (75272472712), we get a palindrome (96999899969).

The spelling of 21727427257 in words is "twenty-one billion, seven hundred twenty-seven million, four hundred twenty-seven thousand, two hundred fifty-seven".