21420452 has 24 divisors (see below), whose sum is σ = 39391296. Its totient is φ = 10172448.

The previous prime is 21420449. The next prime is 21420479. The reversal of 21420452 is 25402412.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13703 + ... + 15185.

It is an arithmetic number, because the mean of its divisors is an integer number (1641304).

Almost surely, 2^21420452 is an apocalyptic number.

It is an amenable number.

21420452 is a deficient number, since it is larger than the sum of its proper divisors (17970844).

21420452 is a wasteful number, since it uses less digits than its factorization.

21420452 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1667 (or 1665 counting only the distinct ones).

The product of its (nonzero) digits is 640, while the sum is 20.

The square root of 21420452 is about 4628.2234172520. The cubic root of 21420452 is about 277.7215264348.

Adding to 21420452 its reverse (25402412), we get a palindrome (46822864).

The spelling of 21420452 in words is "twenty-one million, four hundred twenty thousand, four hundred fifty-two".