101991901 has 4 divisors (see below), whose sum is σ = 111263904. Its totient is φ = 92719900.

The previous prime is 101991863. The next prime is 101991907. The reversal of 101991901 is 109199101.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 101991901 - 2¹⁵ = 101959133 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (101991907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4635985 + ... + 4636006.

It is an arithmetic number, because the mean of its divisors is an integer number (27815976).

Almost surely, 2^101991901 is an apocalyptic number.

101991901 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

101991901 is a deficient number, since it is larger than the sum of its proper divisors (9272003).

101991901 is an equidigital number, since it uses as much as digits as its factorization.

101991901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9272002.

The product of its (nonzero) digits is 729, while the sum is 31.

The square root of 101991901 is about 10099.1039701550. The cubic root of 101991901 is about 467.2205061061.

It can be divided in two parts, 10199 and 1901, that added together give a square (12100 = 110²).

The spelling of 101991901 in words is "one hundred one million, nine hundred ninety-one thousand, nine hundred one".