21980137 has 2 divisors, whose sum is σ = 21980138. Its totient is φ = 21980136.

The previous prime is 21980117. The next prime is 21980171. The reversal of 21980137 is 73108912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17438976 + 4541161 = 4176^2 + 2131^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21980137 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21980099 and 21980108.

It is not a weakly prime, because it can be changed into another prime (21980117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10990068 + 10990069.

It is an arithmetic number, because the mean of its divisors is an integer number (10990069).

Almost surely, 2^21980137 is an apocalyptic number.

It is an amenable number.

21980137 is a deficient number, since it is larger than the sum of its proper divisors (1).

21980137 is an equidigital number, since it uses as much as digits as its factorization.

21980137 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 21980137 is about 4688.2978787615. The cubic root of 21980137 is about 280.1195790264.

The spelling of 21980137 in words is "twenty-one million, nine hundred eighty thousand, one hundred thirty-seven".