21855402 has 12 divisors (see below), whose sum is σ = 47353410. Its totient is φ = 7285128.

The previous prime is 21855401. The next prime is 21855409. The reversal of 21855402 is 20455812.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 15610401 + 6245001 = 3951^2 + 2499^2 .

It is not an unprimeable number, because it can be changed into a prime (21855401) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 607077 + ... + 607112.

Almost surely, 2^21855402 is an apocalyptic number.

21855402 is an abundant number, since it is smaller than the sum of its proper divisors (25498008).

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

21855402 is a wasteful number, since it uses less digits than its factorization.

21855402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1214197 (or 1214194 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 27.

The square root of 21855402 is about 4674.9761496718. The cubic root of 21855402 is about 279.5886903148.

The spelling of 21855402 in words is "twenty-one million, eight hundred fifty-five thousand, four hundred two".