21390001 has 8 divisors (see below), whose sum is σ = 21644064. Its totient is φ = 21137760.

The previous prime is 21389999. The next prime is 21390007. The reversal of 21390001 is 10009312.

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 21390001 - 2¹ = 21389999 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21390007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45570 + ... + 46036.

It is an arithmetic number, because the mean of its divisors is an integer number (2705508).

Almost surely, 2^21390001 is an apocalyptic number.

It is an amenable number.

21390001 is a deficient number, since it is larger than the sum of its proper divisors (254063).

21390001 is a wasteful number, since it uses less digits than its factorization.

21390001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 911.

The product of its (nonzero) digits is 54, while the sum is 16.

The square root of 21390001 is about 4624.9325400486. The cubic root of 21390001 is about 277.5898624100.

Adding to 21390001 its reverse (10009312), we get a palindrome (31399313).

The spelling of 21390001 in words is "twenty-one million, three hundred ninety thousand, one".