21506722 has 8 divisors (see below), whose sum is σ = 32286672. Its totient is φ = 10744500.

The previous prime is 21506707. The next prime is 21506729. The reversal of 21506722 is 22760512.

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 (21506729) 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, 804 + ... + 6607.

It is an arithmetic number, because the mean of its divisors is an integer number (4035834).

Almost surely, 2^21506722 is an apocalyptic number.

21506722 is a deficient number, since it is larger than the sum of its proper divisors (10779950).

21506722 is a wasteful number, since it uses less digits than its factorization.

21506722 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8864.

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 21506722 is about 4637.5340430017. The cubic root of 21506722 is about 278.0938644100.

The spelling of 21506722 in words is "twenty-one million, five hundred six thousand, seven hundred twenty-two".