400630921 has 2 divisors, whose sum is σ = 400630922. Its totient is φ = 400630920.

The previous prime is 400630907. The next prime is 400630927. The reversal of 400630921 is 129036004.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 217975696 + 182655225 = 14764^2 + 13515^2 .

It is a cyclic number.

It is not a de Polignac number, because 400630921 - 2¹¹ = 400628873 is a prime.

It is a super-2 number, since 2×400630921² = 321010269722616482, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (400630927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200315460 + 200315461.

It is an arithmetic number, because the mean of its divisors is an integer number (200315461).

Almost surely, 2^400630921 is an apocalyptic number.

It is an amenable number.

400630921 is a deficient number, since it is larger than the sum of its proper divisors (1).

400630921 is an equidigital number, since it uses as much as digits as its factorization.

400630921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 25.

The square root of 400630921 is about 20015.7668101924. The cubic root of 400630921 is about 737.1934850361.

Adding to 400630921 its reverse (129036004), we get a palindrome (529666925).

The spelling of 400630921 in words is "four hundred million, six hundred thirty thousand, nine hundred twenty-one".