21077838 has 48 divisors (see below), whose sum is σ = 47736000. Its totient is φ = 6713280.

The previous prime is 21077831. The next prime is 21077839. The reversal of 21077838 is 83877012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21077831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 77643 + ... + 77913.

It is an arithmetic number, because the mean of its divisors is an integer number (994500).

Almost surely, 2^21077838 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21077838, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23868000).

21077838 is an abundant number, since it is smaller than the sum of its proper divisors (26658162).

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

21077838 is a wasteful number, since it uses less digits than its factorization.

21077838 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 457 (or 454 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 36.

The square root of 21077838 is about 4591.0606617643. The cubic root of 21077838 is about 276.2328689990.

The spelling of 21077838 in words is "twenty-one million, seventy-seven thousand, eight hundred thirty-eight".