21249145 has 8 divisors (see below), whose sum is σ = 25931520. Its totient is φ = 16710960.

The previous prime is 21249143. The next prime is 21249149. The reversal of 21249145 is 54194212.

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

It is not a de Polignac number, because 21249145 - 2¹ = 21249143 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21249143) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35721 + ... + 36310.

It is an arithmetic number, because the mean of its divisors is an integer number (3241440).

Almost surely, 2^21249145 is an apocalyptic number.

It is an amenable number.

21249145 is a deficient number, since it is larger than the sum of its proper divisors (4682375).

21249145 is an equidigital number, since it uses as much as digits as its factorization.

21249145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72095.

The product of its digits is 2880, while the sum is 28.

The square root of 21249145 is about 4609.6794899429. The cubic root of 21249145 is about 276.9791979582.

The spelling of 21249145 in words is "twenty-one million, two hundred forty-nine thousand, one hundred forty-five".