402002721 has 24 divisors (see below), whose sum is σ = 593260200. Its totient is φ = 262219776.

The previous prime is 402002719. The next prime is 402002729. The reversal of 402002721 is 127200204.

It can be written as a sum of positive squares in 4 ways, for example, as 138297600 + 263705121 = 11760^2 + 16239^2 .

It is not a de Polignac number, because 402002721 - 2¹ = 402002719 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 402002694 and 402002703.

It is not an unprimeable number, because it can be changed into a prime (402002729) 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, 213235 + ... + 215111.

It is an arithmetic number, because the mean of its divisors is an integer number (24719175).

Almost surely, 2^402002721 is an apocalyptic number.

It is an amenable number.

402002721 is a deficient number, since it is larger than the sum of its proper divisors (191257479).

402002721 is a wasteful number, since it uses less digits than its factorization.

402002721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2385 (or 2382 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 18.

The square root of 402002721 is about 20050.0055112212. The cubic root of 402002721 is about 738.0339343684.

Adding to 402002721 its reverse (127200204), we get a palindrome (529202925).

The spelling of 402002721 in words is "four hundred two million, two thousand, seven hundred twenty-one".