21150009 has 6 divisors (see below), whose sum is σ = 30550026. Its totient is φ = 14100000.

The previous prime is 21150001. The next prime is 21150011. The reversal of 21150009 is 90005112.

It can be written as a sum of positive squares in only one way, i.e., 20793600 + 356409 = 4560^2 + 597^2 .

It is not a de Polignac number, because 21150009 - 2³ = 21150001 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21149973 and 21150000.

It is not an unprimeable number, because it can be changed into a prime (21150001) 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, 1174992 + ... + 1175009.

It is an arithmetic number, because the mean of its divisors is an integer number (5091671).

Almost surely, 2^21150009 is an apocalyptic number.

It is an amenable number.

21150009 is a deficient number, since it is larger than the sum of its proper divisors (9400017).

21150009 is a wasteful number, since it uses less digits than its factorization.

21150009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2350007 (or 2350004 counting only the distinct ones).

The product of its (nonzero) digits is 90, while the sum is 18.

The square root of 21150009 is about 4598.9138935188. The cubic root of 21150009 is about 276.5477857344.

The spelling of 21150009 in words is "twenty-one million, one hundred fifty thousand, nine".