402515021 has 2 divisors, whose sum is σ = 402515022. Its totient is φ = 402515020.

The previous prime is 402515017. The next prime is 402515023. The reversal of 402515021 is 120515204.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 311522500 + 90992521 = 17650^2 + 9539^2 .

It is a cyclic number.

It is not a de Polignac number, because 402515021 - 2² = 402515017 is a prime.

Together with 402515023, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 402514984 and 402515002.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (402515023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 201257510 + 201257511.

It is an arithmetic number, because the mean of its divisors is an integer number (201257511).

Almost surely, 2^402515021 is an apocalyptic number.

It is an amenable number.

402515021 is a deficient number, since it is larger than the sum of its proper divisors (1).

402515021 is an equidigital number, since it uses as much as digits as its factorization.

402515021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 402515021 is about 20062.7770012030. Note that the first 3 decimals coincide. The cubic root of 402515021 is about 738.3473105950.

The spelling of 402515021 in words is "four hundred two million, five hundred fifteen thousand, twenty-one".