16401555 has 16 divisors (see below), whose sum is σ = 29158560. Its totient is φ = 8747424.

The previous prime is 16401551. The next prime is 16401563. The reversal of 16401555 is 55510461.

It is a happy number.

16401555 is a `hidden beast` number, since 1 + 640 + 15 + 5 + 5 = 666.

16401555 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 16401555 - 2² = 16401551 is a prime.

It is a super-2 number, since 2×16401555² = 538022012836050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (16401551) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 60612 + ... + 60881.

It is an arithmetic number, because the mean of its divisors is an integer number (1822410).

Almost surely, 2^16401555 is an apocalyptic number.

16401555 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

16401555 is a deficient number, since it is larger than the sum of its proper divisors (12757005).

16401555 is a wasteful number, since it uses less digits than its factorization.

16401555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121507 (or 121501 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 27.

The square root of 16401555 is about 4049.8833316529. The cubic root of 16401555 is about 254.0748482581.

The spelling of 16401555 in words is "sixteen million, four hundred one thousand, five hundred fifty-five".