21478973 has 8 divisors (see below), whose sum is σ = 23272128. Its totient is φ = 19744704.

The previous prime is 21478931. The next prime is 21478979. The reversal of 21478973 is 37987412.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21478973 - 2⁶ = 21478909 is a prime.

It is a super-2 number, since 2×21478973² = 922692562269458, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21478973.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21478979) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13961 + ... + 15422.

It is an arithmetic number, because the mean of its divisors is an integer number (2909016).

Almost surely, 2^21478973 is an apocalyptic number.

It is an amenable number.

21478973 is a deficient number, since it is larger than the sum of its proper divisors (1793155).

21478973 is a wasteful number, since it uses less digits than its factorization.

21478973 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29443.

The product of its digits is 84672, while the sum is 41.

The square root of 21478973 is about 4634.5412933752. The cubic root of 21478973 is about 277.9742096048.

The spelling of 21478973 in words is "twenty-one million, four hundred seventy-eight thousand, nine hundred seventy-three".