21940297 has 8 divisors (see below), whose sum is σ = 22905032. Its totient is φ = 20995200.

The previous prime is 21940291. The next prime is 21940309. The reversal of 21940297 is 79204912.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 441 + 21939856 = 21^2 + 4684^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 21940297 - 2⁷ = 21940169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21940291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2604 + ... + 7117.

It is an arithmetic number, because the mean of its divisors is an integer number (2863129).

Almost surely, 2^21940297 is an apocalyptic number.

It is an amenable number.

21940297 is a deficient number, since it is larger than the sum of its proper divisors (964735).

21940297 is an equidigital number, since it uses as much as digits as its factorization.

21940297 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9819.

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 21940297 is about 4684.0470749129. The cubic root of 21940297 is about 279.9502335021.

The spelling of 21940297 in words is "twenty-one million, nine hundred forty thousand, two hundred ninety-seven".