21880979 has 2 divisors, whose sum is σ = 21880980. Its totient is φ = 21880978.

The previous prime is 21880973. The next prime is 21881017. The reversal of 21880979 is 97908812.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21880979 is a prime.

It is a super-3 number, since 3×21880979³ (a number of 23 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21880973) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10940489 + 10940490.

It is an arithmetic number, because the mean of its divisors is an integer number (10940490).

Almost surely, 2^21880979 is an apocalyptic number.

21880979 is a deficient number, since it is larger than the sum of its proper divisors (1).

21880979 is an equidigital number, since it uses as much as digits as its factorization.

21880979 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 72576, while the sum is 44.

The square root of 21880979 is about 4677.7108717833. The cubic root of 21880979 is about 279.6977137371.

The spelling of 21880979 in words is "twenty-one million, eight hundred eighty thousand, nine hundred seventy-nine".