21072177 has 16 divisors (see below), whose sum is σ = 35678080. Its totient is φ = 12041136.

The previous prime is 21072169. The next prime is 21072187. The reversal of 21072177 is 77127012.

It is not a de Polignac number, because 21072177 - 2³ = 21072169 is a prime.

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

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21072177.

It is not an unprimeable number, because it can be changed into a prime (21072137) 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, 55558 + ... + 55935.

It is an arithmetic number, because the mean of its divisors is an integer number (2229880).

Almost surely, 2^21072177 is an apocalyptic number.

21072177 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21072177 is a deficient number, since it is larger than the sum of its proper divisors (14605903).

21072177 is a wasteful number, since it uses less digits than its factorization.

21072177 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 111509 (or 111503 counting only the distinct ones).

The product of its (nonzero) digits is 1372, while the sum is 27.

The square root of 21072177 is about 4590.4440961632. Note that the first 3 decimals coincide. The cubic root of 21072177 is about 276.2081369513.

Adding to 21072177 its reverse (77127012), we get a palindrome (98199189).

The spelling of 21072177 in words is "twenty-one million, seventy-two thousand, one hundred seventy-seven".