21589451 has 4 divisors (see below), whose sum is σ = 23250192. Its totient is φ = 19928712.

The previous prime is 21589409. The next prime is 21589459. The reversal of 21589451 is 15498512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21589451 - 2¹⁸ = 21327307 is a prime.

It is a super-2 number, since 2×21589451² = 932208788962802, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21589459) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 830351 + ... + 830376.

It is an arithmetic number, because the mean of its divisors is an integer number (5812548).

Almost surely, 2^21589451 is an apocalyptic number.

21589451 is a deficient number, since it is larger than the sum of its proper divisors (1660741).

21589451 is a wasteful number, since it uses less digits than its factorization.

21589451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1660740.

The product of its digits is 14400, while the sum is 35.

The square root of 21589451 is about 4646.4449851472. Note that the first 3 decimals coincide. The cubic root of 21589451 is about 278.4499854855.

The spelling of 21589451 in words is "twenty-one million, five hundred eighty-nine thousand, four hundred fifty-one".