155567991 has 16 divisors (see below), whose sum is σ = 218873600. Its totient is φ = 98013888.

The previous prime is 155567989. The next prime is 155567999. The reversal of 155567991 is 199765551.

It is not a de Polignac number, because 155567991 - 2¹ = 155567989 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 155567991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155567999) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21915 + ... + 28131.

It is an arithmetic number, because the mean of its divisors is an integer number (13679600).

Almost surely, 2^155567991 is an apocalyptic number.

155567991 is a deficient number, since it is larger than the sum of its proper divisors (63305609).

155567991 is a wasteful number, since it uses less digits than its factorization.

155567991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6678.

The product of its digits is 425250, while the sum is 48.

The square root of 155567991 is about 12472.6898061324. The cubic root of 155567991 is about 537.8238795089.

The spelling of 155567991 in words is "one hundred fifty-five million, five hundred sixty-seven thousand, nine hundred ninety-one".