21273513 has 4 divisors (see below), whose sum is σ = 28364688. Its totient is φ = 14182340.

The previous prime is 21273509. The next prime is 21273583. The reversal of 21273513 is 31537212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21273513 - 2² = 21273509 is a prime.

It is a super-2 number, since 2×21273513² = 905124710722338, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21273503) 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, 3545583 + ... + 3545588.

It is an arithmetic number, because the mean of its divisors is an integer number (7091172).

Almost surely, 2^21273513 is an apocalyptic number.

It is an amenable number.

21273513 is a deficient number, since it is larger than the sum of its proper divisors (7091175).

21273513 is an equidigital number, since it uses as much as digits as its factorization.

21273513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7091174.

The product of its digits is 1260, while the sum is 24.

The square root of 21273513 is about 4612.3218664790. The cubic root of 21273513 is about 277.0850351690.

The spelling of 21273513 in words is "twenty-one million, two hundred seventy-three thousand, five hundred thirteen".