21100725 has 36 divisors (see below), whose sum is σ = 38068992. Its totient is φ = 11172000.

The previous prime is 21100711. The next prime is 21100727. The reversal of 21100725 is 52700112.

It is not a de Polignac number, because 21100725 - 2¹¹ = 21098677 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21100698 and 21100707.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21100727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 42730 + ... + 43220.

It is an arithmetic number, because the mean of its divisors is an integer number (1057472).

Almost surely, 2^21100725 is an apocalyptic number.

21100725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21100725 is a deficient number, since it is larger than the sum of its proper divisors (16968267).

21100725 is a wasteful number, since it uses less digits than its factorization.

21100725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 698 (or 690 counting only the distinct ones).

The product of its (nonzero) digits is 140, while the sum is 18.

The square root of 21100725 is about 4593.5525467768. The cubic root of 21100725 is about 276.3328137023.

Adding to 21100725 its reverse (52700112), we get a palindrome (73800837).

The spelling of 21100725 in words is "twenty-one million, one hundred thousand, seven hundred twenty-five".