21870724979 has 4 divisors (see below), whose sum is σ = 21896186520. Its totient is φ = 21845263440.

The previous prime is 21870724963. The next prime is 21870725003. The reversal of 21870724979 is 97942707812.

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

It is a cyclic number.

It is not a de Polignac number, because 21870724979 - 2⁴ = 21870724963 is a prime.

It is a super-2 number, since 2×21870724979² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21870727979) 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 3 ways as a sum of consecutive naturals, for example, 12729482 + ... + 12731199.

It is an arithmetic number, because the mean of its divisors is an integer number (5474046630).

Almost surely, 2^21870724979 is an apocalyptic number.

21870724979 is a deficient number, since it is larger than the sum of its proper divisors (25461541).

21870724979 is an equidigital number, since it uses as much as digits as its factorization.

21870724979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25461540.

The product of its (nonzero) digits is 3556224, while the sum is 56.

The spelling of 21870724979 in words is "twenty-one billion, eight hundred seventy million, seven hundred twenty-four thousand, nine hundred seventy-nine".