21663147 has 8 divisors (see below), whose sum is σ = 31510080. Its totient is φ = 13129160.

The previous prime is 21663139. The next prime is 21663149. The reversal of 21663147 is 74136612.

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

It is not a de Polignac number, because 21663147 - 2³ = 21663139 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21663149) 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 7 ways as a sum of consecutive naturals, for example, 328197 + ... + 328262.

It is an arithmetic number, because the mean of its divisors is an integer number (3938760).

Almost surely, 2^21663147 is an apocalyptic number.

21663147 is a deficient number, since it is larger than the sum of its proper divisors (9846933).

21663147 is a wasteful number, since it uses less digits than its factorization.

21663147 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 656473.

The product of its digits is 6048, while the sum is 30.

The square root of 21663147 is about 4654.3685930532. The cubic root of 21663147 is about 278.7664570978.

Adding to 21663147 its reverse (74136612), we get a palindrome (95799759).

It can be divided in two parts, 2166314 and 7, that added together give a triangular number (2166321 = T₂₀₈₁).

The spelling of 21663147 in words is "twenty-one million, six hundred sixty-three thousand, one hundred forty-seven".