21081026 has 4 divisors (see below), whose sum is σ = 31621542. Its totient is φ = 10540512.

The previous prime is 21081019. The next prime is 21081029. The reversal of 21081026 is 62018012.

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

It can be written as a sum of positive squares in only one way, i.e., 14326225 + 6754801 = 3785^2 + 2599^2 .

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21080989 and 21081007.

It is not an unprimeable number, because it can be changed into a prime (21081029) 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 as a sum of consecutive naturals, namely, 5270255 + ... + 5270258.

Almost surely, 2^21081026 is an apocalyptic number.

21081026 is a deficient number, since it is larger than the sum of its proper divisors (10540516).

21081026 is a wasteful number, since it uses less digits than its factorization.

21081026 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10540515.

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 21081026 is about 4591.4078450950. The cubic root of 21081026 is about 276.2467949370.

Adding to 21081026 its reverse (62018012), we get a palindrome (83099038).

The spelling of 21081026 in words is "twenty-one million, eighty-one thousand, twenty-six".