21140347 has 4 divisors (see below), whose sum is σ = 21203416. Its totient is φ = 21077280.

The previous prime is 21140341. The next prime is 21140351. The reversal of 21140347 is 74304112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21140347 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21140341) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31029 + ... + 31702.

It is an arithmetic number, because the mean of its divisors is an integer number (5300854).

Almost surely, 2^21140347 is an apocalyptic number.

21140347 is a deficient number, since it is larger than the sum of its proper divisors (63069).

21140347 is an equidigital number, since it uses as much as digits as its factorization.

21140347 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63068.

The product of its (nonzero) digits is 672, while the sum is 22.

The square root of 21140347 is about 4597.8633081030. The cubic root of 21140347 is about 276.5056673647.

Adding to 21140347 its reverse (74304112), we get a palindrome (95444459).

The spelling of 21140347 in words is "twenty-one million, one hundred forty thousand, three hundred forty-seven".