165421890 has 96 divisors (see below), whose sum is σ = 447662592. Its totient is φ = 42336000.

The previous prime is 165421889. The next prime is 165421901. The reversal of 165421890 is 98124561.

165421890 is a `hidden beast` number, since 16 + 542 + 18 + 90 = 666.

165421890 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 588550 + ... + 588830.

It is an arithmetic number, because the mean of its divisors is an integer number (4663152).

Almost surely, 2^165421890 is an apocalyptic number.

165421890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 165421890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (223831296).

165421890 is an abundant number, since it is smaller than the sum of its proper divisors (282240702).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

165421890 is a wasteful number, since it uses less digits than its factorization.

165421890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 536 (or 533 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 165421890 is about 12861.6441406221. The cubic root of 165421890 is about 548.9477291052.

The spelling of 165421890 in words is "one hundred sixty-five million, four hundred twenty-one thousand, eight hundred ninety".