21840079 has 2 divisors, whose sum is σ = 21840080. Its totient is φ = 21840078.

The previous prime is 21840061. The next prime is 21840083. The reversal of 21840079 is 97004812.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21840079 - 2⁵ = 21840047 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21840079.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21840029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10920039 + 10920040.

It is an arithmetic number, because the mean of its divisors is an integer number (10920040).

Almost surely, 2^21840079 is an apocalyptic number.

21840079 is a deficient number, since it is larger than the sum of its proper divisors (1).

21840079 is an equidigital number, since it uses as much as digits as its factorization.

21840079 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 21840079 is about 4673.3370304313. The cubic root of 21840079 is about 279.5233344040.

The spelling of 21840079 in words is "twenty-one million, eight hundred forty thousand, seventy-nine".