20981507 has 2 divisors, whose sum is σ = 20981508. Its totient is φ = 20981506.

The previous prime is 20981473. The next prime is 20981509. The reversal of 20981507 is 70518902.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20981507 - 2¹⁰ = 20980483 is a prime.

Together with 20981509, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20981509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10490753 + 10490754.

It is an arithmetic number, because the mean of its divisors is an integer number (10490754).

Almost surely, 2^20981507 is an apocalyptic number.

20981507 is a deficient number, since it is larger than the sum of its proper divisors (1).

20981507 is an equidigital number, since it uses as much as digits as its factorization.

20981507 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5040, while the sum is 32.

The square root of 20981507 is about 4580.5574988204. The cubic root of 20981507 is about 275.8114084814.

The spelling of 20981507 in words is "twenty million, nine hundred eighty-one thousand, five hundred seven".