21261026 has 4 divisors (see below), whose sum is σ = 31891542. Its totient is φ = 10630512.

The previous prime is 21260989. The next prime is 21261029. The reversal of 21261026 is 62016212.

It is a happy number.

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., 19936225 + 1324801 = 4465^2 + 1151^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21260989 and 21261007.

It is not an unprimeable number, because it can be changed into a prime (21261029) 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, 5315255 + ... + 5315258.

Almost surely, 2^21261026 is an apocalyptic number.

21261026 is a deficient number, since it is larger than the sum of its proper divisors (10630516).

21261026 is a wasteful number, since it uses less digits than its factorization.

21261026 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10630515.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21261026 is about 4610.9680111664. The cubic root of 21261026 is about 277.0308106501.

Adding to 21261026 its reverse (62016212), we get a palindrome (83277238).

The spelling of 21261026 in words is "twenty-one million, two hundred sixty-one thousand, twenty-six".