101981921 has 2 divisors, whose sum is σ = 101981922. Its totient is φ = 101981920.

The previous prime is 101981899. The next prime is 101981941. The reversal of 101981921 is 129189101.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 95550625 + 6431296 = 9775^2 + 2536^2 .

It is an emirp because it is prime and its reverse (129189101) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 101981921 - 2⁶ = 101981857 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (101981941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 50990960 + 50990961.

It is an arithmetic number, because the mean of its divisors is an integer number (50990961).

Almost surely, 2^101981921 is an apocalyptic number.

It is an amenable number.

101981921 is a deficient number, since it is larger than the sum of its proper divisors (1).

101981921 is an equidigital number, since it uses as much as digits as its factorization.

101981921 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 32.

The square root of 101981921 is about 10098.6098548266. The cubic root of 101981921 is about 467.2052662923.

The spelling of 101981921 in words is "one hundred one million, nine hundred eighty-one thousand, nine hundred twenty-one".