243402021 has 24 divisors (see below), whose sum is σ = 364708344. Its totient is φ = 156297600.

The previous prime is 243402001. The next prime is 243402041. The reversal of 243402021 is 120204342.

243402021 is a `hidden beast` number, since 243 + 402 + 0 + 21 = 666.

It is an interprime number because it is at equal distance from previous prime (243402001) and next prime (243402041).

It can be written as a sum of positive squares in 4 ways, for example, as 171321921 + 72080100 = 13089^2 + 8490^2 .

It is not a de Polignac number, because 243402021 - 2¹¹ = 243399973 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 243401985 and 243402003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243402001) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30015 + ... + 37251.

It is an arithmetic number, because the mean of its divisors is an integer number (15196181).

Almost surely, 2^243402021 is an apocalyptic number.

It is an amenable number.

243402021 is a deficient number, since it is larger than the sum of its proper divisors (121306323).

243402021 is a wasteful number, since it uses less digits than its factorization.

243402021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7381 (or 7378 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 243402021 is about 15601.3467687889. The cubic root of 243402021 is about 624.3690879209.

Adding to 243402021 its reverse (120204342), we get a palindrome (363606363).

The spelling of 243402021 in words is "two hundred forty-three million, four hundred two thousand, twenty-one".