155861805 has 32 divisors (see below), whose sum is σ = 281439360. Its totient is φ = 72961280.

The previous prime is 155861801. The next prime is 155861813. The reversal of 155861805 is 508168551.

It is not a de Polignac number, because 155861805 - 2² = 155861801 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155861801) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11502 + ... + 21071.

It is an arithmetic number, because the mean of its divisors is an integer number (8794980).

Almost surely, 2^155861805 is an apocalyptic number.

155861805 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

155861805 is a deficient number, since it is larger than the sum of its proper divisors (125577555).

155861805 is a wasteful number, since it uses less digits than its factorization.

155861805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32621.

The product of its (nonzero) digits is 48000, while the sum is 39.

The square root of 155861805 is about 12484.4625434978. The cubic root of 155861805 is about 538.1622541895.

It can be divided in two parts, 15586 and 1805, that added together give a triangular number (17391 = T₁₈₆).

The spelling of 155861805 in words is "one hundred fifty-five million, eight hundred sixty-one thousand, eight hundred five".