21138061 has 8 divisors (see below), whose sum is σ = 24651200. Its totient is φ = 18118044.

The previous prime is 21138059. The next prime is 21138067. The reversal of 21138061 is 16083112.

It is not a de Polignac number, because 21138061 - 2¹ = 21138059 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21138067) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30471 + ... + 31156.

It is an arithmetic number, because the mean of its divisors is an integer number (3081400).

Almost surely, 2^21138061 is an apocalyptic number.

It is an amenable number.

21138061 is a deficient number, since it is larger than the sum of its proper divisors (3513139).

21138061 is an frugal number, since it uses more digits than its factorization.

21138061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61648 (or 61634 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 21138061 is about 4597.6147076500. The cubic root of 21138061 is about 276.4957004085.

The spelling of 21138061 in words is "twenty-one million, one hundred thirty-eight thousand, sixty-one".