21451347 has 6 divisors (see below), whose sum is σ = 30985292. Its totient is φ = 14300892.

The previous prime is 21451343. The next prime is 21451351. The reversal of 21451347 is 74315412.

It is an interprime number because it is at equal distance from previous prime (21451343) and next prime (21451351).

It is not a de Polignac number, because 21451347 - 2² = 21451343 is a prime.

It is a super-2 number, since 2×21451347² = 920320576228818, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21451347.

It is not an unprimeable number, because it can be changed into a prime (21451343) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1191733 + ... + 1191750.

Almost surely, 2^21451347 is an apocalyptic number.

21451347 is a deficient number, since it is larger than the sum of its proper divisors (9533945).

21451347 is a wasteful number, since it uses less digits than its factorization.

21451347 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2383489 (or 2383486 counting only the distinct ones).

The product of its digits is 3360, while the sum is 27.

The square root of 21451347 is about 4631.5598884177. The cubic root of 21451347 is about 277.8549827650.

Adding to 21451347 its reverse (74315412), we get a palindrome (95766759).

The spelling of 21451347 in words is "twenty-one million, four hundred fifty-one thousand, three hundred forty-seven".