402399661 has 2 divisors, whose sum is σ = 402399662. Its totient is φ = 402399660.

The previous prime is 402399659. The next prime is 402399677. The reversal of 402399661 is 166993204.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 327248100 + 75151561 = 18090^2 + 8669^2 .

It is a cyclic number.

It is not a de Polignac number, because 402399661 - 2¹ = 402399659 is a prime.

Together with 402399659, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (402399611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 201199830 + 201199831.

It is an arithmetic number, because the mean of its divisors is an integer number (201199831).

Almost surely, 2^402399661 is an apocalyptic number.

It is an amenable number.

402399661 is a deficient number, since it is larger than the sum of its proper divisors (1).

402399661 is an equidigital number, since it uses as much as digits as its factorization.

402399661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 69984, while the sum is 40.

The square root of 402399661 is about 20059.9018193011. The cubic root of 402399661 is about 738.2767675679.

It can be divided in two parts, 4023 and 99661, that added together give a square (103684 = 322²).

The spelling of 402399661 in words is "four hundred two million, three hundred ninety-nine thousand, six hundred sixty-one".