21587471 has 4 divisors (see below), whose sum is σ = 21636000. Its totient is φ = 21538944.

The previous prime is 21587453. The next prime is 21587491. The reversal of 21587471 is 17478512.

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 21587471 - 2¹⁴ = 21571087 is a prime.

It is a super-3 number, since 3×21587471³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21587411) 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, 23591 + ... + 24488.

It is an arithmetic number, because the mean of its divisors is an integer number (5409000).

Almost surely, 2^21587471 is an apocalyptic number.

21587471 is a deficient number, since it is larger than the sum of its proper divisors (48529).

21587471 is an equidigital number, since it uses as much as digits as its factorization.

21587471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48528.

The product of its digits is 15680, while the sum is 35.

The square root of 21587471 is about 4646.2319141429. The cubic root of 21587471 is about 278.4414728740.

The spelling of 21587471 in words is "twenty-one million, five hundred eighty-seven thousand, four hundred seventy-one".