21251013 has 16 divisors (see below), whose sum is σ = 32476800. Its totient is φ = 12108096.

The previous prime is 21250979. The next prime is 21251017. The reversal of 21251013 is 31015212.

It is not a de Polignac number, because 21251013 - 2¹³ = 21242821 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21250983 and 21251001.

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 polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7063 + ... + 9611.

It is an arithmetic number, because the mean of its divisors is an integer number (2029800).

Almost surely, 2^21251013 is an apocalyptic number.

It is an amenable number.

21251013 is a deficient number, since it is larger than the sum of its proper divisors (11225787).

21251013 is a wasteful number, since it uses less digits than its factorization.

21251013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2956.

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 21251013 is about 4609.8821026139. The cubic root of 21251013 is about 276.9873140806.

Adding to 21251013 its reverse (31015212), we get a palindrome (52266225).

The spelling of 21251013 in words is "twenty-one million, two hundred fifty-one thousand, thirteen".