215021661389 has 2 divisors, whose sum is σ = 215021661390. Its totient is φ = 215021661388.

The previous prime is 215021661331. The next prime is 215021661419. The reversal of 215021661389 is 983166120512.

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., 175364125225 + 39657536164 = 418765^2 + 199142^2 .

It is a cyclic number.

It is not a de Polignac number, because 215021661389 - 2³⁶ = 146302184653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (215021661319) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 107510830694 + 107510830695.

It is an arithmetic number, because the mean of its divisors is an integer number (107510830695).

Almost surely, 2^215021661389 is an apocalyptic number.

It is an amenable number.

215021661389 is a deficient number, since it is larger than the sum of its proper divisors (1).

215021661389 is an equidigital number, since it uses as much as digits as its factorization.

215021661389 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 155520, while the sum is 44.

The spelling of 215021661389 in words is "two hundred fifteen billion, twenty-one million, six hundred sixty-one thousand, three hundred eighty-nine".