21305026 has 4 divisors (see below), whose sum is σ = 31957542. Its totient is φ = 10652512.

The previous prime is 21305003. The next prime is 21305027. The reversal of 21305026 is 62050312.

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., 15992001 + 5313025 = 3999^2 + 2305^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21304994 and 21305012.

It is not an unprimeable number, because it can be changed into a prime (21305027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5326255 + ... + 5326258.

Almost surely, 2^21305026 is an apocalyptic number.

21305026 is a deficient number, since it is larger than the sum of its proper divisors (10652516).

21305026 is a wasteful number, since it uses less digits than its factorization.

21305026 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10652515.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21305026 is about 4615.7367775903. The cubic root of 21305026 is about 277.2217853885.

Adding to 21305026 its reverse (62050312), we get a palindrome (83355338).

The spelling of 21305026 in words is "twenty-one million, three hundred five thousand, twenty-six".