21451071 has 4 divisors (see below), whose sum is σ = 28601432. Its totient is φ = 14300712.

The previous prime is 21451063. The next prime is 21451081. The reversal of 21451071 is 17015412.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21451071 - 2³ = 21451063 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21451081) 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, 3575176 + ... + 3575181.

It is an arithmetic number, because the mean of its divisors is an integer number (7150358).

Almost surely, 2^21451071 is an apocalyptic number.

21451071 is a deficient number, since it is larger than the sum of its proper divisors (7150361).

21451071 is an equidigital number, since it uses as much as digits as its factorization.

21451071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7150360.

The product of its (nonzero) digits is 280, while the sum is 21.

The square root of 21451071 is about 4631.5300927447. The cubic root of 21451071 is about 277.8537911024.

Adding to 21451071 its reverse (17015412), we get a palindrome (38466483).

The spelling of 21451071 in words is "twenty-one million, four hundred fifty-one thousand, seventy-one".