155840421 has 16 divisors (see below), whose sum is σ = 230395968. Its totient is φ = 92899200.

The previous prime is 155840407. The next prime is 155840429. The reversal of 155840421 is 124048551.

It is not a de Polignac number, because 155840421 - 2⁵ = 155840389 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155840429) 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, 36696 + ... + 40721.

It is an arithmetic number, because the mean of its divisors is an integer number (14399748).

Almost surely, 2^155840421 is an apocalyptic number.

155840421 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

155840421 is a deficient number, since it is larger than the sum of its proper divisors (74555547).

155840421 is a wasteful number, since it uses less digits than its factorization.

155840421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77492.

The product of its (nonzero) digits is 6400, while the sum is 30.

The square root of 155840421 is about 12483.6060895881. The cubic root of 155840421 is about 538.1376413859.

Adding to 155840421 its reverse (124048551), we get a palindrome (279888972).

The spelling of 155840421 in words is "one hundred fifty-five million, eight hundred forty thousand, four hundred twenty-one".