21251007 has 12 divisors (see below), whose sum is σ = 30812704. Its totient is φ = 14113440.

The previous prime is 21250979. The next prime is 21251017. The reversal of 21251007 is 70015212.

It is not a de Polignac number, because 21251007 - 2¹¹ = 21248959 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251017) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1918 + ... + 6795.

Almost surely, 2^21251007 is an apocalyptic number.

21251007 is a deficient number, since it is larger than the sum of its proper divisors (9561697).

21251007 is a wasteful number, since it uses less digits than its factorization.

21251007 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8990 (or 8987 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 21251007 is about 4609.8814518380. The cubic root of 21251007 is about 276.9872880124.

Adding to 21251007 its reverse (70015212), we get a palindrome (91266219).

The spelling of 21251007 in words is "twenty-one million, two hundred fifty-one thousand, seven".