21253106 has 16 divisors (see below), whose sum is σ = 37122624. Its totient is φ = 8936304.

The previous prime is 21253103. The next prime is 21253109. The reversal of 21253106 is 60135212.

It is an interprime number because it is at equal distance from previous prime (21253103) and next prime (21253109).

It is not an unprimeable number, because it can be changed into a prime (21253103) 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, 13580 + ... + 15063.

It is an arithmetic number, because the mean of its divisors is an integer number (2320164).

Almost surely, 2^21253106 is an apocalyptic number.

21253106 is a deficient number, since it is larger than the sum of its proper divisors (15869518).

21253106 is a wasteful number, since it uses less digits than its factorization.

21253106 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28705.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 21253106 is about 4610.1091093379. The cubic root of 21253106 is about 276.9964072223.

Adding to 21253106 its reverse (60135212), we get a palindrome (81388318).

The spelling of 21253106 in words is "twenty-one million, two hundred fifty-three thousand, one hundred six".