21687001 has 8 divisors (see below), whose sum is σ = 25099520. Its totient is φ = 18353088.

The previous prime is 21686989. The next prime is 21687077. The reversal of 21687001 is 10078612.

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 21687001 - 2¹³ = 21678809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21687101) 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, 19056 + ... + 20161.

It is an arithmetic number, because the mean of its divisors is an integer number (3137440).

Almost surely, 2^21687001 is an apocalyptic number.

It is an amenable number.

21687001 is a deficient number, since it is larger than the sum of its proper divisors (3412519).

21687001 is an equidigital number, since it uses as much as digits as its factorization.

21687001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39303.

The product of its (nonzero) digits is 672, while the sum is 25.

The square root of 21687001 is about 4656.9304267940. The cubic root of 21687001 is about 278.8687391874.

The spelling of 21687001 in words is "twenty-one million, six hundred eighty-seven thousand, one".