21151249 has 8 divisors (see below), whose sum is σ = 24266880. Its totient is φ = 18059136.

The previous prime is 21151241. The next prime is 21151253. The reversal of 21151249 is 94215112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21151249 - 2³ = 21151241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21151241) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 3904 + ... + 7585.

It is an arithmetic number, because the mean of its divisors is an integer number (3033360).

Almost surely, 2^21151249 is an apocalyptic number.

It is an amenable number.

21151249 is a deficient number, since it is larger than the sum of its proper divisors (3115631).

21151249 is a wasteful number, since it uses less digits than its factorization.

21151249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11759.

The product of its digits is 720, while the sum is 25.

The square root of 21151249 is about 4599.0487059826. The cubic root of 21151249 is about 276.5531901853.

It can be divided in two parts, 2115 and 1249, that added together give a square (3364 = 58²).

The spelling of 21151249 in words is "twenty-one million, one hundred fifty-one thousand, two hundred forty-nine".