21043245351205 has 48 divisors (see below), whose sum is σ = 31898603640960. Its totient is φ = 13044582587520.

The previous prime is 21043245351199. The next prime is 21043245351221. The reversal of 21043245351205 is 50215354234012.

It is a happy number.

It is not a de Polignac number, because 21043245351205 - 2³ = 21043245351197 is a prime.

It is a super-2 number, since 2×21043245351205² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 13121514 + ... + 14637643.

It is an arithmetic number, because the mean of its divisors is an integer number (664554242520).

Almost surely, 2^{21043245351205} is an apocalyptic number.

It is an amenable number.

21043245351205 is a deficient number, since it is larger than the sum of its proper divisors (10855358289755).

21043245351205 is a wasteful number, since it uses less digits than its factorization.

21043245351205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27759370 (or 27759359 counting only the distinct ones).

The product of its (nonzero) digits is 144000, while the sum is 37.

Adding to 21043245351205 its reverse (50215354234012), we get a palindrome (71258599585217).

The spelling of 21043245351205 in words is "twenty-one trillion, forty-three billion, two hundred forty-five million, three hundred fifty-one thousand, two hundred five".