21264247 has 8 divisors (see below), whose sum is σ = 21565440. Its totient is φ = 20965080.

The previous prime is 21264241. The next prime is 21264251. The reversal of 21264247 is 74246212.

It is a happy number.

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 21264247 - 2³ = 21264239 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21264241) 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, 44154 + ... + 44632.

It is an arithmetic number, because the mean of its divisors is an integer number (2695680).

Almost surely, 2^21264247 is an apocalyptic number.

21264247 is a deficient number, since it is larger than the sum of its proper divisors (301193).

21264247 is a wasteful number, since it uses less digits than its factorization.

21264247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1013.

The product of its digits is 5376, while the sum is 28.

The square root of 21264247 is about 4611.3172738384. The cubic root of 21264247 is about 277.0447998022.

The spelling of 21264247 in words is "twenty-one million, two hundred sixty-four thousand, two hundred forty-seven".