21161725 has 48 divisors (see below), whose sum is σ = 31248000. Its totient is φ = 14065920.

The previous prime is 21161717. The next prime is 21161729. The reversal of 21161725 is 52716112.

It is not a de Polignac number, because 21161725 - 2³ = 21161717 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a self number, because there is not a number n which added to its sum of digits gives 21161725.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21161729) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 141951 + ... + 142099.

It is an arithmetic number, because the mean of its divisors is an integer number (651000).

Almost surely, 2^21161725 is an apocalyptic number.

21161725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21161725 is a deficient number, since it is larger than the sum of its proper divisors (10086275).

21161725 is a wasteful number, since it uses less digits than its factorization.

21161725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214 (or 209 counting only the distinct ones).

The product of its digits is 840, while the sum is 25.

The square root of 21161725 is about 4600.1874961788. The cubic root of 21161725 is about 276.5988406500.

Adding to 21161725 its reverse (52716112), we get a palindrome (73877837).

The spelling of 21161725 in words is "twenty-one million, one hundred sixty-one thousand, seven hundred twenty-five".