21030061 has 4 divisors (see below), whose sum is σ = 22647772. Its totient is φ = 19412352.

The previous prime is 21030049. The next prime is 21030083. The reversal of 21030061 is 16003012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1976836 + 19053225 = 1406^2 + 4365^2 .

It is a cyclic number.

It is not a de Polignac number, because 21030061 - 2¹⁵ = 20997293 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (13), and also a Moran number because the ratio is a prime number: 1617697 = 21030061 / (2 + 1 + 0 + 3 + 0 + 0 + 6 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21030001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 808836 + ... + 808861.

It is an arithmetic number, because the mean of its divisors is an integer number (5661943).

Almost surely, 2^21030061 is an apocalyptic number.

It is an amenable number.

21030061 is a deficient number, since it is larger than the sum of its proper divisors (1617711).

21030061 is a wasteful number, since it uses less digits than its factorization.

21030061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1617710.

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 21030061 is about 4585.8544460111. The cubic root of 21030061 is about 276.0239993484.

Adding to 21030061 its reverse (16003012), we get a palindrome (37033073).

The spelling of 21030061 in words is "twenty-one million, thirty thousand, sixty-one".