155121681 has 32 divisors (see below), whose sum is σ = 255790080. Its totient is φ = 82209600.

The previous prime is 155121677. The next prime is 155121689. The reversal of 155121681 is 186121551.

155121681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 155121681 - 2² = 155121677 is a prime.

It is a super-2 number, since 2×155121681² = 48125471832531522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (155121689) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1365 + ... + 17666.

It is an arithmetic number, because the mean of its divisors is an integer number (7993440).

Almost surely, 2^155121681 is an apocalyptic number.

155121681 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

155121681 is a deficient number, since it is larger than the sum of its proper divisors (100668399).

155121681 is a wasteful number, since it uses less digits than its factorization.

155121681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19077.

The product of its digits is 2400, while the sum is 30.

The square root of 155121681 is about 12454.7854658360. The cubic root of 155121681 is about 537.3090647586.

It can be divided in two parts, 1551 and 21681, that added together give a palindrome (23232).

The spelling of 155121681 in words is "one hundred fifty-five million, one hundred twenty-one thousand, six hundred eighty-one".