21125519 has 4 divisors (see below), whose sum is σ = 21188544. Its totient is φ = 21062496.

The previous prime is 21125501. The next prime is 21125521. The reversal of 21125519 is 91552112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21125519 is a prime.

It is a super-2 number, since 2×21125519² = 892575106038722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21125219) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31007 + ... + 31680.

It is an arithmetic number, because the mean of its divisors is an integer number (5297136).

Almost surely, 2^21125519 is an apocalyptic number.

21125519 is a deficient number, since it is larger than the sum of its proper divisors (63025).

21125519 is an equidigital number, since it uses as much as digits as its factorization.

21125519 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63024.

The product of its digits is 900, while the sum is 26.

The square root of 21125519 is about 4596.2505371226. The cubic root of 21125519 is about 276.4410045188.

The spelling of 21125519 in words is "twenty-one million, one hundred twenty-five thousand, five hundred nineteen".