21722745 has 32 divisors (see below), whose sum is σ = 38185344. Its totient is φ = 10457600.

The previous prime is 21722717. The next prime is 21722747. The reversal of 21722745 is 54722712.

It is not a de Polignac number, because 21722745 - 2⁸ = 21722489 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21722747) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 28165 + ... + 28925.

It is an arithmetic number, because the mean of its divisors is an integer number (1193292).

Almost surely, 2^21722745 is an apocalyptic number.

It is an amenable number.

21722745 is a deficient number, since it is larger than the sum of its proper divisors (16462599).

21722745 is a wasteful number, since it uses less digits than its factorization.

21722745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 953.

The product of its digits is 7840, while the sum is 30.

The square root of 21722745 is about 4660.7665678513. The cubic root of 21722745 is about 279.0218633706.

The spelling of 21722745 in words is "twenty-one million, seven hundred twenty-two thousand, seven hundred forty-five".