21252807 has 16 divisors (see below), whose sum is σ = 31599360. Its totient is φ = 14117400.

The previous prime is 21252799. The next prime is 21252809. The reversal of 21252807 is 70825212.

It is not a de Polignac number, because 21252807 - 2³ = 21252799 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21252809) 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 15 ways as a sum of consecutive naturals, for example, 7132 + ... + 9662.

It is an arithmetic number, because the mean of its divisors is an integer number (1974960).

Almost surely, 2^21252807 is an apocalyptic number.

21252807 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21252807 is a deficient number, since it is larger than the sum of its proper divisors (10346553).

21252807 is a wasteful number, since it uses less digits than its factorization.

21252807 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2851 (or 2845 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 21252807 is about 4610.0766804902. The cubic root of 21252807 is about 276.9951082386.

The spelling of 21252807 in words is "twenty-one million, two hundred fifty-two thousand, eight hundred seven".