21947506 has 8 divisors (see below), whose sum is σ = 37624320. Its totient is φ = 9406068.

The previous prime is 21947503. The next prime is 21947507. The reversal of 21947506 is 60574912.

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

It is not an unprimeable number, because it can be changed into a prime (21947503) 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 3 ways as a sum of consecutive naturals, for example, 783826 + ... + 783853.

It is an arithmetic number, because the mean of its divisors is an integer number (4703040).

Almost surely, 2^21947506 is an apocalyptic number.

21947506 is a deficient number, since it is larger than the sum of its proper divisors (15676814).

21947506 is a wasteful number, since it uses less digits than its factorization.

21947506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1567688.

The product of its (nonzero) digits is 15120, while the sum is 34.

The square root of 21947506 is about 4684.8165385637. The cubic root of 21947506 is about 279.9808915531.

The spelling of 21947506 in words is "twenty-one million, nine hundred forty-seven thousand, five hundred six".