400120921 has 4 divisors (see below), whose sum is σ = 400432144. Its totient is φ = 399809700.

The previous prime is 400120901. The next prime is 400120933. The reversal of 400120921 is 129021004.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-400120921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (400120901) 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 3 ways as a sum of consecutive naturals, for example, 153675 + ... + 156256.

It is an arithmetic number, because the mean of its divisors is an integer number (100108036).

Almost surely, 2^400120921 is an apocalyptic number.

It is an amenable number.

400120921 is a deficient number, since it is larger than the sum of its proper divisors (311223).

400120921 is a wasteful number, since it uses less digits than its factorization.

400120921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 311222.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 400120921 is about 20003.0227965675. The cubic root of 400120921 is about 736.8805383765.

Adding to 400120921 its reverse (129021004), we get a palindrome (529141925).

The spelling of 400120921 in words is "four hundred million, one hundred twenty thousand, nine hundred twenty-one".