21507023845 has 16 divisors (see below), whose sum is σ = 26187754032. Its totient is φ = 16953200640.

The previous prime is 21507023843. The next prime is 21507023849. The reversal of 21507023845 is 54832070512.

It can be written as a sum of positive squares in 8 ways, for example, as 885776644 + 20621247201 = 29762^2 + 143601^2 .

It is not a de Polignac number, because 21507023845 - 2¹ = 21507023843 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21507023843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 348525 + ... + 405565.

It is an arithmetic number, because the mean of its divisors is an integer number (1636734627).

Almost surely, 2^21507023845 is an apocalyptic number.

It is an amenable number.

21507023845 is a deficient number, since it is larger than the sum of its proper divisors (4680730187).

21507023845 is a wasteful number, since it uses less digits than its factorization.

21507023845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58152.

The product of its (nonzero) digits is 67200, while the sum is 37.

The spelling of 21507023845 in words is "twenty-one billion, five hundred seven million, twenty-three thousand, eight hundred forty-five".