21558945 has 8 divisors (see below), whose sum is σ = 34494336. Its totient is φ = 11498096.

The previous prime is 21558923. The next prime is 21558949. The reversal of 21558945 is 54985512.

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 21558945 - 2⁵ = 21558913 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21558949) 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, 718617 + ... + 718646.

It is an arithmetic number, because the mean of its divisors is an integer number (4311792).

Almost surely, 2^21558945 is an apocalyptic number.

It is an amenable number.

21558945 is a deficient number, since it is larger than the sum of its proper divisors (12935391).

21558945 is a wasteful number, since it uses less digits than its factorization.

21558945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1437271.

The product of its digits is 72000, while the sum is 39.

The square root of 21558945 is about 4643.1610999404. The cubic root of 21558945 is about 278.3187732671.

The spelling of 21558945 in words is "twenty-one million, five hundred fifty-eight thousand, nine hundred forty-five".