21125513 has 8 divisors (see below), whose sum is σ = 22078848. Its totient is φ = 20193264.

The previous prime is 21125501. The next prime is 21125521. The reversal of 21125513 is 31552112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21125513 - 2⁸ = 21125257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21145513) 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, 3206 + ... + 7247.

It is an arithmetic number, because the mean of its divisors is an integer number (2759856).

Almost surely, 2^21125513 is an apocalyptic number.

It is an amenable number.

21125513 is a deficient number, since it is larger than the sum of its proper divisors (953335).

21125513 is a wasteful number, since it uses less digits than its factorization.

21125513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10543.

The product of its digits is 300, while the sum is 20.

The square root of 21125513 is about 4596.2498844166. The cubic root of 21125513 is about 276.4409783475.

Adding to 21125513 its reverse (31552112), we get a palindrome (52677625).

The spelling of 21125513 in words is "twenty-one million, one hundred twenty-five thousand, five hundred thirteen".