21073523 has 4 divisors (see below), whose sum is σ = 22313160. Its totient is φ = 19833888.

The previous prime is 21073519. The next prime is 21073553. The reversal of 21073523 is 32537012.

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

It is a cyclic number.

It is not a de Polignac number, because 21073523 - 2² = 21073519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21073553) 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, 619793 + ... + 619826.

It is an arithmetic number, because the mean of its divisors is an integer number (5578290).

Almost surely, 2^21073523 is an apocalyptic number.

21073523 is a deficient number, since it is larger than the sum of its proper divisors (1239637).

21073523 is a wasteful number, since it uses less digits than its factorization.

21073523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1239636.

The product of its (nonzero) digits is 1260, while the sum is 23.

The square root of 21073523 is about 4590.5907027310. The cubic root of 21073523 is about 276.2140178219.

The spelling of 21073523 in words is "twenty-one million, seventy-three thousand, five hundred twenty-three".