21252507 has 16 divisors (see below), whose sum is σ = 30466560. Its totient is φ = 13135392.

The previous prime is 21252503. The next prime is 21252509. The reversal of 21252507 is 70525212.

It is not a de Polignac number, because 21252507 - 2² = 21252503 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a plaindrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (21252503) 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, 1288 + ... + 6645.

It is an arithmetic number, because the mean of its divisors is an integer number (1904160).

Almost surely, 2^21252507 is an apocalyptic number.

21252507 is a deficient number, since it is larger than the sum of its proper divisors (9214053).

21252507 is a wasteful number, since it uses less digits than its factorization.

21252507 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8002.

The product of its (nonzero) digits is 1400, while the sum is 24.

The square root of 21252507 is about 4610.0441429557. The cubic root of 21252507 is about 276.9938048982.

Adding to 21252507 its reverse (70525212), we get a palindrome (91777719).

The spelling of 21252507 in words is "twenty-one million, two hundred fifty-two thousand, five hundred seven".