155121665 has 8 divisors (see below), whose sum is σ = 187396200. Its totient is φ = 123263872.

The previous prime is 155121647. The next prime is 155121671. The reversal of 155121665 is 566121551.

It can be written as a sum of positive squares in 4 ways, for example, as 1560001 + 153561664 = 1249^2 + 12392^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 155121665 - 2¹² = 155117569 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 103364 + ... + 104853.

It is an arithmetic number, because the mean of its divisors is an integer number (23424525).

Almost surely, 2^155121665 is an apocalyptic number.

It is an amenable number.

155121665 is a deficient number, since it is larger than the sum of its proper divisors (32274535).

155121665 is a wasteful number, since it uses less digits than its factorization.

155121665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 208371.

The product of its digits is 9000, while the sum is 32.

The square root of 155121665 is about 12454.7848235126. The cubic root of 155121665 is about 537.3090462850.

The spelling of 155121665 in words is "one hundred fifty-five million, one hundred twenty-one thousand, six hundred sixty-five".