21402404 has 6 divisors (see below), whose sum is σ = 37454214. Its totient is φ = 10701200.

The previous prime is 21402401. The next prime is 21402419. The reversal of 21402404 is 40420412.

It can be written as a sum of positive squares in only one way, i.e., 12390400 + 9012004 = 3520^2 + 3002^2 .

It is not an unprimeable number, because it can be changed into a prime (21402401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2675297 + ... + 2675304.

It is an arithmetic number, because the mean of its divisors is an integer number (6242369).

Almost surely, 2^21402404 is an apocalyptic number.

It is an amenable number.

21402404 is a deficient number, since it is larger than the sum of its proper divisors (16051810).

21402404 is a wasteful number, since it uses less digits than its factorization.

21402404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5350605 (or 5350603 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 17.

The square root of 21402404 is about 4626.2732301497. The cubic root of 21402404 is about 277.6435055712.

Adding to 21402404 its reverse (40420412), we get a palindrome (61822816).

The spelling of 21402404 in words is "twenty-one million, four hundred two thousand, four hundred four".