21671401 has 4 divisors (see below), whose sum is σ = 21976704. Its totient is φ = 21366100.

The previous prime is 21671393. The next prime is 21671417. The reversal of 21671401 is 10417612.

It is the 1901-st star number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21671401 - 2³ = 21671393 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21671431) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 152545 + ... + 152686.

It is an arithmetic number, because the mean of its divisors is an integer number (5494176).

Almost surely, 2^21671401 is an apocalyptic number.

It is an amenable number.

21671401 is a deficient number, since it is larger than the sum of its proper divisors (305303).

21671401 is an equidigital number, since it uses as much as digits as its factorization.

21671401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305302.

The product of its (nonzero) digits is 336, while the sum is 22.

The square root of 21671401 is about 4655.2552024567. The cubic root of 21671401 is about 278.8018574048.

It can be divided in two parts, 216 and 71401, that added together give a palindrome (71617).

The spelling of 21671401 in words is "twenty-one million, six hundred seventy-one thousand, four hundred one".