21979071 has 12 divisors (see below), whose sum is σ = 32842680. Its totient is φ = 14147280.

The previous prime is 21979043. The next prime is 21979081. The reversal of 21979071 is 17097912.

It is not a de Polignac number, because 21979071 - 2¹¹ = 21977023 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21979021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41845 + ... + 42366.

It is an arithmetic number, because the mean of its divisors is an integer number (2736890).

Almost surely, 2^21979071 is an apocalyptic number.

21979071 is a deficient number, since it is larger than the sum of its proper divisors (10863609).

21979071 is a wasteful number, since it uses less digits than its factorization.

21979071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84246 (or 84243 counting only the distinct ones).

The product of its (nonzero) digits is 7938, while the sum is 36.

The square root of 21979071 is about 4688.1841900676. The cubic root of 21979071 is about 280.1150505090.

The spelling of 21979071 in words is "twenty-one million, nine hundred seventy-nine thousand, seventy-one".