402530021 has 4 divisors (see below), whose sum is σ = 402594912. Its totient is φ = 402465132.

The previous prime is 402530003. The next prime is 402530047. The reversal of 402530021 is 120035204.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-402530021 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (402530081) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22025 + ... + 35918.

It is an arithmetic number, because the mean of its divisors is an integer number (100648728).

Almost surely, 2^402530021 is an apocalyptic number.

It is an amenable number.

402530021 is a deficient number, since it is larger than the sum of its proper divisors (64891).

402530021 is an equidigital number, since it uses as much as digits as its factorization.

402530021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64890.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 402530021 is about 20063.1508243346. The cubic root of 402530021 is about 738.3564821551.

Adding to 402530021 its reverse (120035204), we get a palindrome (522565225).

The spelling of 402530021 in words is "four hundred two million, five hundred thirty thousand, twenty-one".