155402121 has 16 divisors (see below), whose sum is σ = 249267200. Its totient is φ = 84127248.

The previous prime is 155402111. The next prime is 155402131. The reversal of 155402121 is 121204551.

155402121 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (155402111) and next prime (155402131).

It is not a de Polignac number, because 155402121 - 2⁵ = 155402089 is a prime.

It is a super-2 number, since 2×155402121² = 48299638422597282, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is not an unprimeable number, because it can be changed into a prime (155402111) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 194341 + ... + 195138.

It is an arithmetic number, because the mean of its divisors is an integer number (15579200).

Almost surely, 2^155402121 is an apocalyptic number.

It is an amenable number.

155402121 is a deficient number, since it is larger than the sum of its proper divisors (93865079).

155402121 is a wasteful number, since it uses less digits than its factorization.

155402121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 389508.

The product of its (nonzero) digits is 400, while the sum is 21.

The square root of 155402121 is about 12466.0387052183. The cubic root of 155402121 is about 537.6326649996.

Adding to 155402121 its reverse (121204551), we get a palindrome (276606672).

The spelling of 155402121 in words is "one hundred fifty-five million, four hundred two thousand, one hundred twenty-one".