21452421 has 4 divisors (see below), whose sum is σ = 28603232. Its totient is φ = 14301612.

The previous prime is 21452413. The next prime is 21452443. The reversal of 21452421 is 12425412.

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 not a de Polignac number, because 21452421 - 2³ = 21452413 is a prime.

It is a super-2 number, since 2×21452421² = 920412733522482, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21452411) 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, 3575401 + ... + 3575406.

It is an arithmetic number, because the mean of its divisors is an integer number (7150808).

Almost surely, 2^21452421 is an apocalyptic number.

It is an amenable number.

21452421 is a deficient number, since it is larger than the sum of its proper divisors (7150811).

21452421 is an equidigital number, since it uses as much as digits as its factorization.

21452421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7150810.

The product of its digits is 640, while the sum is 21.

The square root of 21452421 is about 4631.6758306255. The cubic root of 21452421 is about 277.8596197896.

Adding to 21452421 its reverse (12425412), we get a palindrome (33877833).

The spelling of 21452421 in words is "twenty-one million, four hundred fifty-two thousand, four hundred twenty-one".