21755477247 has 16 divisors (see below), whose sum is σ = 33165734400. Its totient is φ = 12426252192.

The previous prime is 21755477213. The next prime is 21755477257. The reversal of 21755477247 is 74277455712.

It is not a de Polignac number, because 21755477247 - 2²⁴ = 21738700031 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21755477247.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21755477257) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 177747 + ... + 274052.

It is an arithmetic number, because the mean of its divisors is an integer number (2072858400).

Almost surely, 2^21755477247 is an apocalyptic number.

21755477247 is a deficient number, since it is larger than the sum of its proper divisors (11410257153).

21755477247 is a wasteful number, since it uses less digits than its factorization.

21755477247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 454102.

The product of its digits is 3841600, while the sum is 51.

The spelling of 21755477247 in words is "twenty-one billion, seven hundred fifty-five million, four hundred seventy-seven thousand, two hundred forty-seven".