400202021 has 2 divisors, whose sum is σ = 400202022. Its totient is φ = 400202020.

The previous prime is 400202017. The next prime is 400202051. The reversal of 400202021 is 120202004.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 259660996 + 140541025 = 16114^2 + 11855^2 .

It is a cyclic number.

It is not a de Polignac number, because 400202021 - 2² = 400202017 is a prime.

It is a super-2 number, since 2×400202021² = 320323315224968882, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 400201993 and 400202011.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400202051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200101010 + 200101011.

It is an arithmetic number, because the mean of its divisors is an integer number (200101011).

Almost surely, 2^400202021 is an apocalyptic number.

It is an amenable number.

400202021 is a deficient number, since it is larger than the sum of its proper divisors (1).

400202021 is an equidigital number, since it uses as much as digits as its factorization.

400202021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 11.

The square root of 400202021 is about 20005.0498874659. The cubic root of 400202021 is about 736.9303208059.

Adding to 400202021 its reverse (120202004), we get a palindrome (520404025).

The spelling of 400202021 in words is "four hundred million, two hundred two thousand, twenty-one".