155457781 has 4 divisors (see below), whose sum is σ = 155488032. Its totient is φ = 155427532.

The previous prime is 155457769. The next prime is 155457803. The reversal of 155457781 is 187754551.

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, and also an emirpimes, since its reverse is a distinct semiprime: 187754551 = 1993 ⋅94207.

It is a cyclic number.

It is not a de Polignac number, because 155457781 - 2⁵ = 155457749 is a prime.

It is a super-2 number, since 2×155457781² = 48334243346887922, 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 (155457761) 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, 5281 + ... + 18406.

It is an arithmetic number, because the mean of its divisors is an integer number (38872008).

Almost surely, 2^155457781 is an apocalyptic number.

It is an amenable number.

155457781 is a deficient number, since it is larger than the sum of its proper divisors (30251).

155457781 is an equidigital number, since it uses as much as digits as its factorization.

155457781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30250.

The product of its digits is 196000, while the sum is 43.

The square root of 155457781 is about 12468.2709707481. The cubic root of 155457781 is about 537.6968448662.

The spelling of 155457781 in words is "one hundred fifty-five million, four hundred fifty-seven thousand, seven hundred eighty-one".