400121555 has 8 divisors (see below), whose sum is σ = 496702800. Its totient is φ = 309059296.

The previous prime is 400121467. The next prime is 400121569. The reversal of 400121555 is 555121004.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 400121555 - 2¹⁰ = 400120531 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 400121555.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1379585 + ... + 1379874.

It is an arithmetic number, because the mean of its divisors is an integer number (62087850).

Almost surely, 2^400121555 is an apocalyptic number.

400121555 is a deficient number, since it is larger than the sum of its proper divisors (96581245).

400121555 is a wasteful number, since it uses less digits than its factorization.

400121555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2759493.

The product of its (nonzero) digits is 1000, while the sum is 23.

The square root of 400121555 is about 20003.0386441660. The cubic root of 400121555 is about 736.8809275772.

Adding to 400121555 its reverse (555121004), we get a palindrome (955242559).

The spelling of 400121555 in words is "four hundred million, one hundred twenty-one thousand, five hundred fifty-five".