21995437 has 8 divisors (see below), whose sum is σ = 22297880. Its totient is φ = 21695040.

The previous prime is 21995431. The next prime is 21995447. The reversal of 21995437 is 73459912.

It can be written as a sum of positive squares in 4 ways, for example, as 4405801 + 17589636 = 2099^2 + 4194^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21995437 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21995437.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21995431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40387 + ... + 40927.

It is an arithmetic number, because the mean of its divisors is an integer number (2787235).

Almost surely, 2^21995437 is an apocalyptic number.

It is an amenable number.

21995437 is a deficient number, since it is larger than the sum of its proper divisors (302443).

21995437 is a wasteful number, since it uses less digits than its factorization.

21995437 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1023.

The product of its digits is 68040, while the sum is 40.

The square root of 21995437 is about 4689.9293171646. The cubic root of 21995437 is about 280.1845594450.

The spelling of 21995437 in words is "twenty-one million, nine hundred ninety-five thousand, four hundred thirty-seven".