16121538 has 48 divisors (see below), whose sum is σ = 37856160. Its totient is φ = 5084856.

The previous prime is 16121537. The next prime is 16121561. The reversal of 16121538 is 83512161.

16121538 is a `hidden beast` number, since 1 + 6 + 121 + 538 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (16121531) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19081 + ... + 19907.

It is an arithmetic number, because the mean of its divisors is an integer number (788670).

Almost surely, 2^16121538 is an apocalyptic number.

16121538 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 16121538, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (18928080).

16121538 is an abundant number, since it is smaller than the sum of its proper divisors (21734622).

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

16121538 is a wasteful number, since it uses less digits than its factorization.

16121538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 876 (or 851 counting only the distinct ones).

The product of its digits is 1440, while the sum is 27.

The square root of 16121538 is about 4015.1635085012. The cubic root of 16121538 is about 252.6206357513.

Adding to 16121538 its reverse (83512161), we get a palindrome (99633699).

It can be divided in two parts, 1612153 and 8, that added together give a palindrome (1612161).

The spelling of 16121538 in words is "sixteen million, one hundred twenty-one thousand, five hundred thirty-eight".