155381999 has 8 divisors (see below), whose sum is σ = 156359040. Its totient is φ = 154408536.

The previous prime is 155381983. The next prime is 155382001. The reversal of 155381999 is 999183551.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 155381999 - 2⁴ = 155381983 is a prime.

It is a super-2 number, since 2×155381999² = 48287131226472002, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155381929) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 174734 + ... + 175620.

It is an arithmetic number, because the mean of its divisors is an integer number (19544880).

Almost surely, 2^155381999 is an apocalyptic number.

155381999 is a deficient number, since it is larger than the sum of its proper divisors (977041).

155381999 is an equidigital number, since it uses as much as digits as its factorization.

155381999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1789.

The product of its digits is 437400, while the sum is 50.

The square root of 155381999 is about 12465.2316063521. The cubic root of 155381999 is about 537.6094591571.

The spelling of 155381999 in words is "one hundred fifty-five million, three hundred eighty-one thousand, nine hundred ninety-nine".