21045973 has 16 divisors (see below), whose sum is σ = 23388736. Its totient is φ = 18817920.

The previous prime is 21045961. The next prime is 21046001. The reversal of 21045973 is 37954012.

It is a cyclic number.

It is not a de Polignac number, because 21045973 - 2⁹ = 21045461 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21040973) 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, 63418 + ... + 63748.

It is an arithmetic number, because the mean of its divisors is an integer number (1461796).

Almost surely, 2^21045973 is an apocalyptic number.

It is an amenable number.

21045973 is a deficient number, since it is larger than the sum of its proper divisors (2342763).

21045973 is a wasteful number, since it uses less digits than its factorization.

21045973 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 484.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 21045973 is about 4587.5890182099. The cubic root of 21045973 is about 276.0935979199.

Adding to 21045973 its reverse (37954012), we get a palindrome (58999985).

The spelling of 21045973 in words is "twenty-one million, forty-five thousand, nine hundred seventy-three".