21385473 has 16 divisors (see below), whose sum is σ = 30476160. Its totient is φ = 13291776.

The previous prime is 21385471. The next prime is 21385513. The reversal of 21385473 is 37458312.

It is not a de Polignac number, because 21385473 - 2¹ = 21385471 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21385471) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3636 + ... + 7482.

It is an arithmetic number, because the mean of its divisors is an integer number (1904760).

Almost surely, 2^21385473 is an apocalyptic number.

It is an amenable number.

21385473 is a deficient number, since it is larger than the sum of its proper divisors (9090687).

21385473 is a wasteful number, since it uses less digits than its factorization.

21385473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3976.

The product of its digits is 20160, while the sum is 33.

The square root of 21385473 is about 4624.4429934858. The cubic root of 21385473 is about 277.5702735750.

The spelling of 21385473 in words is "twenty-one million, three hundred eighty-five thousand, four hundred seventy-three".