21868625 has 16 divisors (see below), whose sum is σ = 27512784. Its totient is φ = 17353600.

The previous prime is 21868619. The next prime is 21868631. The reversal of 21868625 is 52686812.

It is an interprime number because it is at equal distance from previous prime (21868619) and next prime (21868631).

It can be written as a sum of positive squares in 8 ways, for example, as 4695889 + 17172736 = 2167^2 + 4144^2 .

It is not a de Polignac number, because 21868625 - 2¹² = 21864529 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16487 + ... + 17763.

It is an arithmetic number, because the mean of its divisors is an integer number (1719549).

Almost surely, 2^21868625 is an apocalyptic number.

21868625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21868625 is a deficient number, since it is larger than the sum of its proper divisors (5644159).

21868625 is a wasteful number, since it uses less digits than its factorization.

21868625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1429 (or 1419 counting only the distinct ones).

The product of its digits is 46080, while the sum is 38.

The square root of 21868625 is about 4676.3901676400. The cubic root of 21868625 is about 279.6450647207.

The spelling of 21868625 in words is "twenty-one million, eight hundred sixty-eight thousand, six hundred twenty-five".