20751881 has 2 divisors, whose sum is σ = 20751882. Its totient is φ = 20751880.

The previous prime is 20751877. The next prime is 20751923. The reversal of 20751881 is 18815702.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13808656 + 6943225 = 3716^2 + 2635^2 .

It is a cyclic number.

It is not a de Polignac number, because 20751881 - 2² = 20751877 is a prime.

It is a super-2 number, since 2×20751881² = 861281130076322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20751481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10375940 + 10375941.

It is an arithmetic number, because the mean of its divisors is an integer number (10375941).

Almost surely, 2^20751881 is an apocalyptic number.

It is an amenable number.

20751881 is a deficient number, since it is larger than the sum of its proper divisors (1).

20751881 is an equidigital number, since it uses as much as digits as its factorization.

20751881 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4480, while the sum is 32.

The square root of 20751881 is about 4555.4232514663. The cubic root of 20751881 is about 274.8015361446.

The spelling of 20751881 in words is "twenty million, seven hundred fifty-one thousand, eight hundred eighty-one".