155778491 has 4 divisors (see below), whose sum is σ = 169940184. Its totient is φ = 141616800.

The previous prime is 155778487. The next prime is 155778499. The reversal of 155778491 is 194877551.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 155778491 - 2² = 155778487 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155778499) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7080830 + ... + 7080851.

It is an arithmetic number, because the mean of its divisors is an integer number (42485046).

Almost surely, 2^155778491 is an apocalyptic number.

155778491 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

155778491 is a deficient number, since it is larger than the sum of its proper divisors (14161693).

155778491 is a wasteful number, since it uses less digits than its factorization.

155778491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14161692.

The product of its digits is 352800, while the sum is 47.

The square root of 155778491 is about 12481.1253899638. The cubic root of 155778491 is about 538.0663477735.

The spelling of 155778491 in words is "one hundred fifty-five million, seven hundred seventy-eight thousand, four hundred ninety-one".