21401001 has 6 divisors (see below), whose sum is σ = 30912570. Its totient is φ = 14267328.

The previous prime is 21400997. The next prime is 21401047. The reversal of 21401001 is 10010412.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 19713600 + 1687401 = 4440^2 + 1299^2 .

It is not a de Polignac number, because 21401001 - 2² = 21400997 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 2377889 = 21401001 / (2 + 1 + 4 + 0 + 1 + 0 + 0 + 1).

It is not an unprimeable number, because it can be changed into a prime (21401071) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1188936 + ... + 1188953.

It is an arithmetic number, because the mean of its divisors is an integer number (5152095).

Almost surely, 2^21401001 is an apocalyptic number.

It is an amenable number.

21401001 is a deficient number, since it is larger than the sum of its proper divisors (9511569).

21401001 is a wasteful number, since it uses less digits than its factorization.

21401001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2377895 (or 2377892 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

The square root of 21401001 is about 4626.1215937327. The cubic root of 21401001 is about 277.6374386148.

Adding to 21401001 its reverse (10010412), we get a palindrome (31411413).

The spelling of 21401001 in words is "twenty-one million, four hundred one thousand, one".