21945001 has 4 divisors (see below), whose sum is σ = 23633092. Its totient is φ = 20256912.

The previous prime is 21944987. The next prime is 21945017. The reversal of 21945001 is 10054912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 14784025 + 7160976 = 3845^2 + 2676^2 .

It is not a de Polignac number, because 21945001 - 2¹¹ = 21942953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21945101) 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, 844026 + ... + 844051.

It is an arithmetic number, because the mean of its divisors is an integer number (5908273).

Almost surely, 2^21945001 is an apocalyptic number.

It is an amenable number.

21945001 is a deficient number, since it is larger than the sum of its proper divisors (1688091).

21945001 is a wasteful number, since it uses less digits than its factorization.

21945001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1688090.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 21945001 is about 4684.5491778825. The cubic root of 21945001 is about 279.9702391838.

Adding to 21945001 its reverse (10054912), we get a palindrome (31999913).

The spelling of 21945001 in words is "twenty-one million, nine hundred forty-five thousand, one".