155256781 has 4 divisors (see below), whose sum is σ = 155680192. Its totient is φ = 154833372.

The previous prime is 155256763. The next prime is 155256799. The reversal of 155256781 is 187652551.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (155256763) and next prime (155256799).

It is a cyclic number.

It is not a de Polignac number, because 155256781 - 2¹¹ = 155254733 is a prime.

It is a super-2 number, since 2×155256781² = 48209336092963922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155256281) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 211155 + ... + 211888.

It is an arithmetic number, because the mean of its divisors is an integer number (38920048).

Almost surely, 2^155256781 is an apocalyptic number.

It is an amenable number.

155256781 is a deficient number, since it is larger than the sum of its proper divisors (423411).

155256781 is an equidigital number, since it uses as much as digits as its factorization.

155256781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 423410.

The product of its digits is 84000, while the sum is 40.

The square root of 155256781 is about 12460.2079035624. The cubic root of 155256781 is about 537.4650055458.

The spelling of 155256781 in words is "one hundred fifty-five million, two hundred fifty-six thousand, seven hundred eighty-one".