21970825 has 6 divisors (see below), whose sum is σ = 27243854. Its totient is φ = 17576640.

The previous prime is 21970811. The next prime is 21970829. The reversal of 21970825 is 52807912.

It can be written as a sum of positive squares in 3 ways, for example, as 3489424 + 18481401 = 1868^2 + 4299^2 .

It is not a de Polignac number, because 21970825 - 2¹⁵ = 21938057 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21970829) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 439392 + ... + 439441.

Almost surely, 2^21970825 is an apocalyptic number.

21970825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21970825 is a deficient number, since it is larger than the sum of its proper divisors (5273029).

21970825 is an equidigital number, since it uses as much as digits as its factorization.

21970825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 878843 (or 878838 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 21970825 is about 4687.3046625966. The cubic root of 21970825 is about 280.0800153972.

The spelling of 21970825 in words is "twenty-one million, nine hundred seventy thousand, eight hundred twenty-five".