21487847 has 8 divisors (see below), whose sum is σ = 22966416. Its totient is φ = 20033152.

The previous prime is 21487783. The next prime is 21487891. The reversal of 21487847 is 74878412.

It is a happy number.

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 21487847 - 2⁶ = 21487783 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21487547) 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, 4088 + ... + 7725.

It is an arithmetic number, because the mean of its divisors is an integer number (2870802).

Almost surely, 2^21487847 is an apocalyptic number.

21487847 is a deficient number, since it is larger than the sum of its proper divisors (1478569).

21487847 is a wasteful number, since it uses less digits than its factorization.

21487847 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11937.

The product of its digits is 100352, while the sum is 41.

The square root of 21487847 is about 4635.4985708120. The cubic root of 21487847 is about 278.0124858530.

The spelling of 21487847 in words is "twenty-one million, four hundred eighty-seven thousand, eight hundred forty-seven".