21578073 has 8 divisors (see below), whose sum is σ = 31386336. Its totient is φ = 13077600.

The previous prime is 21578033. The next prime is 21578093. The reversal of 21578073 is 37087512.

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

It is not a de Polignac number, because 21578073 - 2⁸ = 21577817 is a prime.

It is a super-2 number, since 2×21578073² = 931226468786658, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 653881 = 21578073 / (2 + 1 + 5 + 7 + 8 + 0 + 7 + 3).

It is not an unprimeable number, because it can be changed into a prime (21578003) 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, 326908 + ... + 326973.

It is an arithmetic number, because the mean of its divisors is an integer number (3923292).

Almost surely, 2^21578073 is an apocalyptic number.

It is an amenable number.

21578073 is a deficient number, since it is larger than the sum of its proper divisors (9808263).

21578073 is a wasteful number, since it uses less digits than its factorization.

21578073 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 653895.

The product of its (nonzero) digits is 11760, while the sum is 33.

The square root of 21578073 is about 4645.2204468679. The cubic root of 21578073 is about 278.4010609642.

The spelling of 21578073 in words is "twenty-one million, five hundred seventy-eight thousand, seventy-three".