21001473 has 6 divisors (see below), whose sum is σ = 30335474. Its totient is φ = 14000976.

The previous prime is 21001469. The next prime is 21001493. The reversal of 21001473 is 37410012.

It can be written as a sum of positive squares in only one way, i.e., 20142144 + 859329 = 4488^2 + 927^2 .

It is not a de Polignac number, because 21001473 - 2² = 21001469 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21001493) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1166740 + ... + 1166757.

Almost surely, 2^21001473 is an apocalyptic number.

It is an amenable number.

21001473 is a deficient number, since it is larger than the sum of its proper divisors (9334001).

21001473 is a wasteful number, since it uses less digits than its factorization.

21001473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2333503 (or 2333500 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 21001473 is about 4582.7364096138. The cubic root of 21001473 is about 275.8988681148.

Adding to 21001473 its reverse (37410012), we get a palindrome (58411485).

The spelling of 21001473 in words is "twenty-one million, one thousand, four hundred seventy-three".