215846561621 has 2 divisors, whose sum is σ = 215846561622. Its totient is φ = 215846561620.

The previous prime is 215846561617. The next prime is 215846561629. The reversal of 215846561621 is 126165648512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 185016118225 + 30830443396 = 430135^2 + 175586^2 .

It is a cyclic number.

It is not a de Polignac number, because 215846561621 - 2² = 215846561617 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (215846561629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107923280810 + 107923280811.

It is an arithmetic number, because the mean of its divisors is an integer number (107923280811).

Almost surely, 2^215846561621 is an apocalyptic number.

It is an amenable number.

215846561621 is a deficient number, since it is larger than the sum of its proper divisors (1).

215846561621 is an equidigital number, since it uses as much as digits as its factorization.

215846561621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 691200, while the sum is 47.

The spelling of 215846561621 in words is "two hundred fifteen billion, eight hundred forty-six million, five hundred sixty-one thousand, six hundred twenty-one".