155982221 has 2 divisors, whose sum is σ = 155982222. Its totient is φ = 155982220.

The previous prime is 155982217. The next prime is 155982241. The reversal of 155982221 is 122289551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 135606025 + 20376196 = 11645^2 + 4514^2 .

It is a cyclic number.

It is not a de Polignac number, because 155982221 - 2² = 155982217 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155982241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77991110 + 77991111.

It is an arithmetic number, because the mean of its divisors is an integer number (77991111).

Almost surely, 2^155982221 is an apocalyptic number.

It is an amenable number.

155982221 is a deficient number, since it is larger than the sum of its proper divisors (1).

155982221 is an equidigital number, since it uses as much as digits as its factorization.

155982221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 14400, while the sum is 35.

The square root of 155982221 is about 12489.2842469054. The cubic root of 155982221 is about 538.3008099751.

The spelling of 155982221 in words is "one hundred fifty-five million, nine hundred eighty-two thousand, two hundred twenty-one".