400021693 has 2 divisors, whose sum is σ = 400021694. Its totient is φ = 400021692.

The previous prime is 400021673. The next prime is 400021717. The reversal of 400021693 is 396120004.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 343064484 + 56957209 = 18522^2 + 7547^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-400021693 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (400021663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 200010846 + 200010847.

It is an arithmetic number, because the mean of its divisors is an integer number (200010847).

Almost surely, 2^400021693 is an apocalyptic number.

It is an amenable number.

400021693 is a deficient number, since it is larger than the sum of its proper divisors (1).

400021693 is an equidigital number, since it uses as much as digits as its factorization.

400021693 is an evil number, because the sum of its binary digits is even.

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

The square root of 400021693 is about 20000.5423176473. The cubic root of 400021693 is about 736.8196191032.

Adding to 400021693 its reverse (396120004), we get a palindrome (796141697).

The spelling of 400021693 in words is "four hundred million, twenty-one thousand, six hundred ninety-three".