21486247 has 4 divisors (see below), whose sum is σ = 21630600. Its totient is φ = 21341896.

The previous prime is 21486239. The next prime is 21486251. The reversal of 21486247 is 74268412.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21486247 - 2³ = 21486239 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21486277) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 71953 + ... + 72250.

It is an arithmetic number, because the mean of its divisors is an integer number (5407650).

Almost surely, 2^21486247 is an apocalyptic number.

21486247 is a deficient number, since it is larger than the sum of its proper divisors (144353).

21486247 is a wasteful number, since it uses less digits than its factorization.

21486247 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 144352.

The product of its digits is 21504, while the sum is 34.

The square root of 21486247 is about 4635.3259863790. The cubic root of 21486247 is about 278.0055853475.

The spelling of 21486247 in words is "twenty-one million, four hundred eighty-six thousand, two hundred forty-seven".