21663430 has 16 divisors (see below), whose sum is σ = 39047184. Its totient is φ = 8653600.

The previous prime is 21663427. The next prime is 21663431. The reversal of 21663430 is 3436612.

It is a junction number, because it is equal to n+sod(n) for n = 21663395 and 21663404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21663431) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13764 + ... + 15256.

It is an arithmetic number, because the mean of its divisors is an integer number (2440449).

Almost surely, 2^21663430 is an apocalyptic number.

21663430 is a deficient number, since it is larger than the sum of its proper divisors (17383754).

21663430 is a wasteful number, since it uses less digits than its factorization.

21663430 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2951.

The product of its (nonzero) digits is 2592, while the sum is 25.

The square root of 21663430 is about 4654.3989944997. The cubic root of 21663430 is about 278.7676709959.

The spelling of 21663430 in words is "twenty-one million, six hundred sixty-three thousand, four hundred thirty".