21027138 has 32 divisors (see below), whose sum is σ = 46274112. Its totient is φ = 6369440.

The previous prime is 21027133. The next prime is 21027143. The reversal of 21027138 is 83172012.

It is an interprime number because it is at equal distance from previous prime (21027133) and next prime (21027143).

It is not an unprimeable number, because it can be changed into a prime (21027131) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6670 + ... + 9302.

It is an arithmetic number, because the mean of its divisors is an integer number (1446066).

Almost surely, 2^21027138 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21027138, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23137056).

21027138 is an abundant number, since it is smaller than the sum of its proper divisors (25246974).

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

21027138 is a wasteful number, since it uses less digits than its factorization.

21027138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2671 (or 2649 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 21027138 is about 4585.5357375120. The cubic root of 21027138 is about 276.0112104247.

The spelling of 21027138 in words is "twenty-one million, twenty-seven thousand, one hundred thirty-eight".