21663402 has 16 divisors (see below), whose sum is σ = 43390080. Its totient is φ = 7210592.

The previous prime is 21663391. The next prime is 21663403. The reversal of 21663402 is 20436612.

It is not an unprimeable number, because it can be changed into a prime (21663403) 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, 2623 + ... + 7085.

It is an arithmetic number, because the mean of its divisors is an integer number (2711880).

Almost surely, 2^21663402 is an apocalyptic number.

21663402 is an abundant number, since it is smaller than the sum of its proper divisors (21726678).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21663402 is a wasteful number, since it uses less digits than its factorization.

21663402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5277.

The product of its (nonzero) digits is 1728, while the sum is 24.

The square root of 21663402 is about 4654.3959865916. The cubic root of 21663402 is about 278.7675508934.

The spelling of 21663402 in words is "twenty-one million, six hundred sixty-three thousand, four hundred two".