21722505 has 32 divisors (see below), whose sum is σ = 39896064. Its totient is φ = 9886656.

The previous prime is 21722489. The next prime is 21722509. The reversal of 21722505 is 50522712.

It is not a de Polignac number, because 21722505 - 2⁴ = 21722489 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21722509) 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 31 ways as a sum of consecutive naturals, for example, 46282 + ... + 46748.

It is an arithmetic number, because the mean of its divisors is an integer number (1246752).

Almost surely, 2^21722505 is an apocalyptic number.

It is an amenable number.

21722505 is a deficient number, since it is larger than the sum of its proper divisors (18173559).

21722505 is a wasteful number, since it uses less digits than its factorization.

21722505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 925.

The product of its (nonzero) digits is 1400, while the sum is 24.

The square root of 21722505 is about 4660.7408209425. The cubic root of 21722505 is about 279.0208357919.

It can be divided in two parts, 217 and 22505, that added together give a palindrome (22722).

The spelling of 21722505 in words is "twenty-one million, seven hundred twenty-two thousand, five hundred five".