21073513 has 4 divisors (see below), whose sum is σ = 21091968. Its totient is φ = 21055060.

The previous prime is 21073511. The next prime is 21073519. The reversal of 21073513 is 31537012.

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 21073513 - 2¹ = 21073511 is a prime.

It is a super-2 number, since 2×21073513² = 888185900322338, which contains 22 as substring.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21073511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7393 + ... + 9838.

It is an arithmetic number, because the mean of its divisors is an integer number (5272992).

Almost surely, 2^21073513 is an apocalyptic number.

It is an amenable number.

21073513 is a deficient number, since it is larger than the sum of its proper divisors (18455).

21073513 is a wasteful number, since it uses less digits than its factorization.

21073513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18454.

The product of its (nonzero) digits is 630, while the sum is 22.

The square root of 21073513 is about 4590.5896135464. The cubic root of 21073513 is about 276.2139741313.

The spelling of 21073513 in words is "twenty-one million, seventy-three thousand, five hundred thirteen".