21009445245 has 24 divisors (see below), whose sum is σ = 36422539296. Its totient is φ = 11203139808.

The previous prime is 21009445217. The next prime is 21009445267. The reversal of 21009445245 is 54254490012.

It is a happy number.

It is not a de Polignac number, because 21009445245 - 2⁹ = 21009444733 is a prime.

It is a super-2 number, since 2×21009445245² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 252894 + ... + 325536.

It is an arithmetic number, because the mean of its divisors is an integer number (1517605804).

Almost surely, 2^21009445245 is an apocalyptic number.

It is an amenable number.

21009445245 is a deficient number, since it is larger than the sum of its proper divisors (15413094051).

21009445245 is a wasteful number, since it uses less digits than its factorization.

21009445245 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79081 (or 79078 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 36.

The spelling of 21009445245 in words is "twenty-one billion, nine million, four hundred forty-five thousand, two hundred forty-five".