21447739 has 8 divisors (see below), whose sum is σ = 22011120. Its totient is φ = 20891136.

The previous prime is 21447719. The next prime is 21447743. The reversal of 21447739 is 93774412.

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 21447739 - 2⁷ = 21447611 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21447698 and 21447707.

It is not an unprimeable number, because it can be changed into a prime (21447709) 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, 5059 + ... + 8275.

It is an arithmetic number, because the mean of its divisors is an integer number (2751390).

Almost surely, 2^21447739 is an apocalyptic number.

21447739 is a deficient number, since it is larger than the sum of its proper divisors (563381).

21447739 is a wasteful number, since it uses less digits than its factorization.

21447739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3389.

The product of its digits is 42336, while the sum is 37.

The square root of 21447739 is about 4631.1703704355. The cubic root of 21447739 is about 277.8394039921.

The spelling of 21447739 in words is "twenty-one million, four hundred forty-seven thousand, seven hundred thirty-nine".