21812140061 has 4 divisors (see below), whose sum is σ = 21812437500. Its totient is φ = 21811842624.

The previous prime is 21812140057. The next prime is 21812140079. The reversal of 21812140061 is 16004121812.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 8204917561 + 13607222500 = 90581^2 + 116650^2 .

It is a cyclic number.

It is not a de Polignac number, because 21812140061 - 2² = 21812140057 is a prime.

It is a Duffinian number.

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 21812140061.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21812143061) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 48155 + ... + 214343.

It is an arithmetic number, because the mean of its divisors is an integer number (5453109375).

Almost surely, 2^21812140061 is an apocalyptic number.

It is an amenable number.

21812140061 is a deficient number, since it is larger than the sum of its proper divisors (297439).

21812140061 is a wasteful number, since it uses less digits than its factorization.

21812140061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 297438.

The product of its (nonzero) digits is 768, while the sum is 26.

Adding to 21812140061 its reverse (16004121812), we get a palindrome (37816261873).

The spelling of 21812140061 in words is "twenty-one billion, eight hundred twelve million, one hundred forty thousand, sixty-one".