21478247 has 8 divisors (see below), whose sum is σ = 24576000. Its totient is φ = 18387864.

The previous prime is 21478231. The next prime is 21478253. The reversal of 21478247 is 74287412.

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 21478247 - 2⁴ = 21478231 is a prime.

It is a super-2 number, since 2×21478247² = 922630188386018, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21478207) 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, 7754 + ... + 10152.

It is an arithmetic number, because the mean of its divisors is an integer number (3072000).

Almost surely, 2^21478247 is an apocalyptic number.

21478247 is a deficient number, since it is larger than the sum of its proper divisors (3097753).

21478247 is a wasteful number, since it uses less digits than its factorization.

21478247 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3685.

The product of its digits is 25088, while the sum is 35.

The square root of 21478247 is about 4634.4629678098. The cubic root of 21478247 is about 277.9710776805.

The spelling of 21478247 in words is "twenty-one million, four hundred seventy-eight thousand, two hundred forty-seven".