215561105381 has 2 divisors, whose sum is σ = 215561105382. Its totient is φ = 215561105380.

The previous prime is 215561105371. The next prime is 215561105387. The reversal of 215561105381 is 183501165512.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 166308180481 + 49252924900 = 407809^2 + 221930^2 .

It is a cyclic number.

It is not a de Polignac number, because 215561105381 - 2¹⁴ = 215561088997 is a prime.

It is a super-2 number, since 2×215561105381² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (215561105387) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107780552690 + 107780552691.

It is an arithmetic number, because the mean of its divisors is an integer number (107780552691).

Almost surely, 2^215561105381 is an apocalyptic number.

It is an amenable number.

215561105381 is a deficient number, since it is larger than the sum of its proper divisors (1).

215561105381 is an equidigital number, since it uses as much as digits as its factorization.

215561105381 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 36000, while the sum is 38.

The spelling of 215561105381 in words is "two hundred fifteen billion, five hundred sixty-one million, one hundred five thousand, three hundred eighty-one".