21245404 has 6 divisors (see below), whose sum is σ = 37179464. Its totient is φ = 10622700.

The previous prime is 21245387. The next prime is 21245407. The reversal of 21245404 is 40454212.

It is a happy number.

It is a super-2 number, since 2×21245404² = 902734382246432, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21245407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2655672 + ... + 2655679.

Almost surely, 2^21245404 is an apocalyptic number.

It is an amenable number.

21245404 is a deficient number, since it is larger than the sum of its proper divisors (15934060).

21245404 is a wasteful number, since it uses less digits than its factorization.

21245404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5311355 (or 5311353 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 22.

The square root of 21245404 is about 4609.2736954969. The cubic root of 21245404 is about 276.9629425592.

Adding to 21245404 its reverse (40454212), we get a palindrome (61699616).

The spelling of 21245404 in words is "twenty-one million, two hundred forty-five thousand, four hundred four".