155500421 has 2 divisors, whose sum is σ = 155500422. Its totient is φ = 155500420.

The previous prime is 155500363. The next prime is 155500441. The reversal of 155500421 is 124005551.

It is a happy number.

155500421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 151044100 + 4456321 = 12290^2 + 2111^2 .

It is a cyclic number.

It is not a de Polignac number, because 155500421 - 2²² = 151306117 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155500441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77750210 + 77750211.

It is an arithmetic number, because the mean of its divisors is an integer number (77750211).

Almost surely, 2^155500421 is an apocalyptic number.

It is an amenable number.

155500421 is a deficient number, since it is larger than the sum of its proper divisors (1).

155500421 is an equidigital number, since it uses as much as digits as its factorization.

155500421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1000, while the sum is 23.

The square root of 155500421 is about 12469.9807938906. The cubic root of 155500421 is about 537.7460014012.

Adding to 155500421 its reverse (124005551), we get a palindrome (279505972).

The spelling of 155500421 in words is "one hundred fifty-five million, five hundred thousand, four hundred twenty-one".