155778861 has 32 divisors (see below), whose sum is σ = 242142208. Its totient is φ = 87246720.

The previous prime is 155778827. The next prime is 155778863. The reversal of 155778861 is 168877551.

It is not a de Polignac number, because 155778861 - 2⁶ = 155778797 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 155778861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155778863) 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, 470466 + ... + 470796.

It is an arithmetic number, because the mean of its divisors is an integer number (7566944).

Almost surely, 2^155778861 is an apocalyptic number.

It is an amenable number.

155778861 is a deficient number, since it is larger than the sum of its proper divisors (86363347).

155778861 is a wasteful number, since it uses less digits than its factorization.

155778861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 721.

The product of its digits is 470400, while the sum is 48.

The square root of 155778861 is about 12481.1402123364. The cubic root of 155778861 is about 538.0667737724.

The spelling of 155778861 in words is "one hundred fifty-five million, seven hundred seventy-eight thousand, eight hundred sixty-one".