205401103551 has 24 divisors (see below), whose sum is σ = 343366932480. Its totient is φ = 115886334096.

The previous prime is 205401103493. The next prime is 205401103561. The reversal of 205401103551 is 155301104502.

205401103551 is a `hidden beast` number, since 2 + 0 + 5 + 4 + 0 + 1 + 103 + 551 = 666.

It is not a de Polignac number, because 205401103551 - 2²⁷ = 205266885823 is a prime.

It is a super-2 number, since 2×205401103551² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205401103561) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20630055 + ... + 20640008.

It is an arithmetic number, because the mean of its divisors is an integer number (14306955520).

Almost surely, 2^205401103551 is an apocalyptic number.

205401103551 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

205401103551 is a deficient number, since it is larger than the sum of its proper divisors (137965828929).

205401103551 is a wasteful number, since it uses less digits than its factorization.

205401103551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41270155 (or 41270152 counting only the distinct ones).

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

The spelling of 205401103551 in words is "two hundred five billion, four hundred one million, one hundred three thousand, five hundred fifty-one".