155021421 has 8 divisors (see below), whose sum is σ = 213362944. Its totient is φ = 100013760.

The previous prime is 155021401. The next prime is 155021429. The reversal of 155021421 is 124120551.

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

It is not a de Polignac number, because 155021421 - 2²⁶ = 87912557 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155021429) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 833356 + ... + 833541.

It is an arithmetic number, because the mean of its divisors is an integer number (26670368).

Almost surely, 2^155021421 is an apocalyptic number.

It is an amenable number.

155021421 is a deficient number, since it is larger than the sum of its proper divisors (58341523).

155021421 is a wasteful number, since it uses less digits than its factorization.

155021421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1666931.

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

The square root of 155021421 is about 12450.7598563301. The cubic root of 155021421 is about 537.1932799185.

Adding to 155021421 its reverse (124120551), we get a palindrome (279141972).

The spelling of 155021421 in words is "one hundred fifty-five million, twenty-one thousand, four hundred twenty-one".