21150729 has 6 divisors (see below), whose sum is σ = 30551066. Its totient is φ = 14100480.

The previous prime is 21150719. The next prime is 21150739. The reversal of 21150729 is 92705112.

It is an interprime number because it is at equal distance from previous prime (21150719) and next prime (21150739).

It can be written as a sum of positive squares in only one way, i.e., 13860729 + 7290000 = 3723^2 + 2700^2 .

It is not a de Polignac number, because 21150729 - 2¹² = 21146633 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21150709) 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, 1175032 + ... + 1175049.

Almost surely, 2^21150729 is an apocalyptic number.

It is an amenable number.

21150729 is a deficient number, since it is larger than the sum of its proper divisors (9400337).

21150729 is a wasteful number, since it uses less digits than its factorization.

21150729 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2350087 (or 2350084 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

The square root of 21150729 is about 4598.9921722047. The cubic root of 21150729 is about 276.5509238284.

The spelling of 21150729 in words is "twenty-one million, one hundred fifty thousand, seven hundred twenty-nine".