21451047 has 8 divisors (see below), whose sum is σ = 28923120. Its totient is φ = 14139840.

The previous prime is 21451033. The next prime is 21451063. The reversal of 21451047 is 74015412.

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

It is a de Polignac number, because none of the positive numbers 2^k-21451047 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21451007) 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, 39904 + ... + 40437.

It is an arithmetic number, because the mean of its divisors is an integer number (3615390).

Almost surely, 2^21451047 is an apocalyptic number.

21451047 is a deficient number, since it is larger than the sum of its proper divisors (7472073).

21451047 is an equidigital number, since it uses as much as digits as its factorization.

21451047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80433.

The product of its (nonzero) digits is 1120, while the sum is 24.

The square root of 21451047 is about 4631.5275018076. The cubic root of 21451047 is about 277.8536874791.

Adding to 21451047 its reverse (74015412), we get a palindrome (95466459).

The spelling of 21451047 in words is "twenty-one million, four hundred fifty-one thousand, forty-seven".