21907241865 has 24 divisors (see below), whose sum is σ = 38399217480. Its totient is φ = 11552580864.

The previous prime is 21907241849. The next prime is 21907241887. The reversal of 21907241865 is 56814270912.

21907241865 is a `hidden beast` number, since 21 + 90 + 72 + 418 + 65 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 15968016 + 21891273849 = 3996^2 + 147957^2 .

It is not a de Polignac number, because 21907241865 - 2⁴ = 21907241849 is a prime.

It is a super-2 number, since 2×21907241865² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21907241865.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2730982 + ... + 2738991.

It is an arithmetic number, because the mean of its divisors is an integer number (1599967395).

Almost surely, 2^21907241865 is an apocalyptic number.

It is an amenable number.

21907241865 is a deficient number, since it is larger than the sum of its proper divisors (16491975615).

21907241865 is a wasteful number, since it uses less digits than its factorization.

21907241865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5470073 (or 5470070 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 45.

The spelling of 21907241865 in words is "twenty-one billion, nine hundred seven million, two hundred forty-one thousand, eight hundred sixty-five".