21401009 has 8 divisors (see below), whose sum is σ = 24503808. Its totient is φ = 18309600.

The previous prime is 21400997. The next prime is 21401047. The reversal of 21401009 is 90010412.

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 21401009 - 2²⁰ = 20352433 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21401069) 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, 1664 + ... + 6750.

It is an arithmetic number, because the mean of its divisors is an integer number (3062976).

Almost surely, 2^21401009 is an apocalyptic number.

It is an amenable number.

21401009 is a deficient number, since it is larger than the sum of its proper divisors (3102799).

21401009 is an equidigital number, since it uses as much as digits as its factorization.

21401009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5695.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21401009 is about 4626.1224583878. The cubic root of 21401009 is about 277.6374732098.

The spelling of 21401009 in words is "twenty-one million, four hundred one thousand, nine".