155519981 has 2 divisors, whose sum is σ = 155519982. Its totient is φ = 155519980.

The previous prime is 155519971. The next prime is 155519989. The reversal of 155519981 is 189915551.

155519981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 121110025 + 34409956 = 11005^2 + 5866^2 .

It is a cyclic number.

It is not a de Polignac number, because 155519981 - 2²² = 151325677 is a prime.

It is a super-2 number, since 2×155519981² = 48372928980480722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155519989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77759990 + 77759991.

It is an arithmetic number, because the mean of its divisors is an integer number (77759991).

Almost surely, 2^155519981 is an apocalyptic number.

It is an amenable number.

155519981 is a deficient number, since it is larger than the sum of its proper divisors (1).

155519981 is an equidigital number, since it uses as much as digits as its factorization.

155519981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 81000, while the sum is 44.

The square root of 155519981 is about 12470.7650527143. The cubic root of 155519981 is about 537.7685476870.

The spelling of 155519981 in words is "one hundred fifty-five million, five hundred nineteen thousand, nine hundred eighty-one".