155640019 has 4 divisors (see below), whose sum is σ = 159846544. Its totient is φ = 151433496.

The previous prime is 155640007. The next prime is 155640029. The reversal of 155640019 is 910046551.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 910046551 = 12007 ⋅75793.

It is a cyclic number.

It is not a de Polignac number, because 155640019 - 2¹⁹ = 155115731 is a prime.

It is a super-2 number, since 2×155640019² = 48447631028640722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155640029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2103207 + ... + 2103280.

It is an arithmetic number, because the mean of its divisors is an integer number (39961636).

Almost surely, 2^155640019 is an apocalyptic number.

155640019 is a deficient number, since it is larger than the sum of its proper divisors (4206525).

155640019 is an equidigital number, since it uses as much as digits as its factorization.

155640019 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4206524.

The product of its (nonzero) digits is 5400, while the sum is 31.

The square root of 155640019 is about 12475.5769004884. The cubic root of 155640019 is about 537.9068708772.

The spelling of 155640019 in words is "one hundred fifty-five million, six hundred forty thousand, nineteen".