21840402 has 16 divisors (see below), whose sum is σ = 43731072. Its totient is φ = 7271760.

The previous prime is 21840391. The next prime is 21840407. The reversal of 21840402 is 20404812.

It is not an unprimeable number, because it can be changed into a prime (21840407) 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, 5908 + ... + 8864.

It is an arithmetic number, because the mean of its divisors is an integer number (2733192).

Almost surely, 2^21840402 is an apocalyptic number.

21840402 is an abundant number, since it is smaller than the sum of its proper divisors (21890670).

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

21840402 is a wasteful number, since it uses less digits than its factorization.

21840402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4193.

The product of its (nonzero) digits is 512, while the sum is 21.

The square root of 21840402 is about 4673.3715880508. The cubic root of 21840402 is about 279.5247123843.

The spelling of 21840402 in words is "twenty-one million, eight hundred forty thousand, four hundred two".