21145291 has 8 divisors (see below), whose sum is σ = 21523968. Its totient is φ = 20769000.

The previous prime is 21145261. The next prime is 21145301. The reversal of 21145291 is 19254112.

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 a de Polignac number, because none of the positive numbers 2^k-21145291 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21145261) 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, 30256 + ... + 30946.

It is an arithmetic number, because the mean of its divisors is an integer number (2690496).

Almost surely, 2^21145291 is an apocalyptic number.

21145291 is a deficient number, since it is larger than the sum of its proper divisors (378677).

21145291 is an equidigital number, since it uses as much as digits as its factorization.

21145291 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1193.

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

The square root of 21145291 is about 4598.4009177104. The cubic root of 21145291 is about 276.5272207395.

The spelling of 21145291 in words is "twenty-one million, one hundred forty-five thousand, two hundred ninety-one".