21377538 has 96 divisors (see below), whose sum is σ = 58985472. Its totient is φ = 5443200.

The previous prime is 21377519. The next prime is 21377549. The reversal of 21377538 is 83577312.

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, 50568 + ... + 50988.

It is an arithmetic number, because the mean of its divisors is an integer number (614432).

Almost surely, 2^21377538 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21377538, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29492736).

21377538 is an abundant number, since it is smaller than the sum of its proper divisors (37607934).

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

21377538 is a wasteful number, since it uses less digits than its factorization.

21377538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 480 (or 477 counting only the distinct ones).

The product of its digits is 35280, while the sum is 36.

The square root of 21377538 is about 4623.5849727241. The cubic root of 21377538 is about 277.5359388565.

The spelling of 21377538 in words is "twenty-one million, three hundred seventy-seven thousand, five hundred thirty-eight".