21247974 has 32 divisors (see below), whose sum is σ = 51511680. Its totient is φ = 6438600.

The previous prime is 21247937. The next prime is 21247979. The reversal of 21247974 is 47974212.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21247979) 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 15 ways as a sum of consecutive naturals, for example, 17292 + ... + 18479.

It is an arithmetic number, because the mean of its divisors is an integer number (1609740).

Almost surely, 2^21247974 is an apocalyptic number.

21247974 is an abundant number, since it is smaller than the sum of its proper divisors (30263706).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21247974 is a wasteful number, since it uses less digits than its factorization.

21247974 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35793 (or 35787 counting only the distinct ones).

The product of its digits is 28224, while the sum is 36.

The square root of 21247974 is about 4609.5524728546. The cubic root of 21247974 is about 276.9741099324.

The spelling of 21247974 in words is "twenty-one million, two hundred forty-seven thousand, nine hundred seventy-four".