221661544609829 has 2 divisors, whose sum is σ = 221661544609830. Its totient is φ = 221661544609828.

The previous prime is 221661544609823. The next prime is 221661544609849. The reversal of 221661544609829 is 928906445166122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 188671569793729 + 32989974816100 = 13735777^2 + 5743690^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221661544609829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221661544609823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110830772304914 + 110830772304915.

It is an arithmetic number, because the mean of its divisors is an integer number (110830772304915).

Almost surely, 2^{221661544609829} is an apocalyptic number.

It is an amenable number.

221661544609829 is a deficient number, since it is larger than the sum of its proper divisors (1).

221661544609829 is an equidigital number, since it uses as much as digits as its factorization.

221661544609829 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 89579520, while the sum is 65.

The spelling of 221661544609829 in words is "two hundred twenty-one trillion, six hundred sixty-one billion, five hundred forty-four million, six hundred nine thousand, eight hundred twenty-nine".