21791506 has 8 divisors (see below), whose sum is σ = 35658864. Its totient is φ = 9905220.

The previous prime is 21791491. The next prime is 21791507. The reversal of 21791506 is 60519712.

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 (21791507) 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, 495240 + ... + 495283.

It is an arithmetic number, because the mean of its divisors is an integer number (4457358).

Almost surely, 2^21791506 is an apocalyptic number.

21791506 is a deficient number, since it is larger than the sum of its proper divisors (13867358).

21791506 is a wasteful number, since it uses less digits than its factorization.

21791506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 990536.

The product of its (nonzero) digits is 3780, while the sum is 31.

The square root of 21791506 is about 4668.1373158895. The cubic root of 21791506 is about 279.3159577914.

The spelling of 21791506 in words is "twenty-one million, seven hundred ninety-one thousand, five hundred six".