400120021 has 8 divisors (see below), whose sum is σ = 459278720. Its totient is φ = 341461008.

The previous prime is 400120013. The next prime is 400120051. The reversal of 400120021 is 120021004.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 400120021 - 2³ = 400120013 is a prime.

It is a super-3 number, since 3×400120021³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (400120001) 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 in 7 ways as a sum of consecutive naturals, for example, 123201 + ... + 126406.

It is an arithmetic number, because the mean of its divisors is an integer number (57409840).

Almost surely, 2^400120021 is an apocalyptic number.

It is an amenable number.

400120021 is a deficient number, since it is larger than the sum of its proper divisors (59158699).

400120021 is a wasteful number, since it uses less digits than its factorization.

400120021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 249843.

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 400120021 is about 20003.0002999550. Note that the first 3 decimals coincide. The cubic root of 400120021 is about 736.8799858827.

Adding to 400120021 its reverse (120021004), we get a palindrome (520141025).

The spelling of 400120021 in words is "four hundred million, one hundred twenty thousand, twenty-one".