155220001 has 4 divisors (see below), whose sum is σ = 155709972. Its totient is φ = 154730032.

The previous prime is 155219993. The next prime is 155220017. The reversal of 155220001 is 100022551.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 100022551 = 151 ⋅662401.

It can be written as a sum of positive squares in 2 ways, for example, as 82373776 + 72846225 = 9076^2 + 8535^2 .

It is a cyclic number.

It is not a de Polignac number, because 155220001 - 2³ = 155219993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155220071) 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, 244510 + ... + 245143.

It is an arithmetic number, because the mean of its divisors is an integer number (38927493).

Almost surely, 2^155220001 is an apocalyptic number.

It is an amenable number.

155220001 is a deficient number, since it is larger than the sum of its proper divisors (489971).

155220001 is an equidigital number, since it uses as much as digits as its factorization.

155220001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 489970.

The product of its (nonzero) digits is 100, while the sum is 16.

The square root of 155220001 is about 12458.7319178157. The cubic root of 155220001 is about 537.4225607564.

Adding to 155220001 its reverse (100022551), we get a palindrome (255242552).

The spelling of 155220001 in words is "one hundred fifty-five million, two hundred twenty thousand, one".