100631981 has 2 divisors, whose sum is σ = 100631982. Its totient is φ = 100631980.

The previous prime is 100631963. The next prime is 100632011. The reversal of 100631981 is 189136001.

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., 89965225 + 10666756 = 9485^2 + 3266^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-100631981 is a prime.

It is a super-2 number, since 2×100631981² = 20253591199968722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (100631941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 50315990 + 50315991.

It is an arithmetic number, because the mean of its divisors is an integer number (50315991).

Almost surely, 2^100631981 is an apocalyptic number.

It is an amenable number.

100631981 is a deficient number, since it is larger than the sum of its proper divisors (1).

100631981 is an equidigital number, since it uses as much as digits as its factorization.

100631981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1296, while the sum is 29.

The square root of 100631981 is about 10031.5492821398. The cubic root of 100631981 is about 465.1346293800.

Adding to 100631981 its reverse (189136001), we get a palindrome (289767982).

The spelling of 100631981 in words is "one hundred million, six hundred thirty-one thousand, nine hundred eighty-one".