155424721 has 4 divisors (see below), whose sum is σ = 157297392. Its totient is φ = 153552052.

The previous prime is 155424713. The next prime is 155424739. The reversal of 155424721 is 127424551.

155424721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 a cyclic number.

It is not a de Polignac number, because 155424721 - 2³ = 155424713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155424221) 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, 936211 + ... + 936376.

It is an arithmetic number, because the mean of its divisors is an integer number (39324348).

Almost surely, 2^155424721 is an apocalyptic number.

It is an amenable number.

155424721 is a deficient number, since it is larger than the sum of its proper divisors (1872671).

155424721 is an equidigital number, since it uses as much as digits as its factorization.

155424721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1872670.

The product of its digits is 11200, while the sum is 31.

The square root of 155424721 is about 12466.9451350361. The cubic root of 155424721 is about 537.6587262254.

The spelling of 155424721 in words is "one hundred fifty-five million, four hundred twenty-four thousand, seven hundred twenty-one".