1861612361621 has 4 divisors (see below), whose sum is σ = 1861631239692. Its totient is φ = 1861593483552.

The previous prime is 1861612361617. The next prime is 1861612361647. The reversal of 1861612361621 is 1261632161681.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 967103095396 + 894509266225 = 983414^2 + 945785^2 .

It is a cyclic number.

It is not a de Polignac number, because 1861612361621 - 2² = 1861612361617 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 (1861612361821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9290336 + ... + 9488601.

It is an arithmetic number, because the mean of its divisors is an integer number (465407809923).

Almost surely, 2^{1861612361621} is an apocalyptic number.

It is an amenable number.

1861612361621 is a deficient number, since it is larger than the sum of its proper divisors (18878071).

1861612361621 is an equidigital number, since it uses as much as digits as its factorization.

1861612361621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18878070.

The product of its digits is 124416, while the sum is 44.

The spelling of 1861612361621 in words is "one trillion, eight hundred sixty-one billion, six hundred twelve million, three hundred sixty-one thousand, six hundred twenty-one".