100991554 has 4 divisors (see below), whose sum is σ = 151487334. Its totient is φ = 50495776.

The previous prime is 100991497. The next prime is 100991557. The reversal of 100991554 is 455199001.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 58936329 + 42055225 = 7677^2 + 6485^2 .

It is not an unprimeable number, because it can be changed into a prime (100991557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25247887 + ... + 25247890.

Almost surely, 2^100991554 is an apocalyptic number.

100991554 is a deficient number, since it is larger than the sum of its proper divisors (50495780).

100991554 is an equidigital number, since it uses as much as digits as its factorization.

100991554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50495779.

The product of its (nonzero) digits is 8100, while the sum is 34.

The square root of 100991554 is about 10049.4554081303. The cubic root of 100991554 is about 465.6879691966.

The spelling of 100991554 in words is "one hundred million, nine hundred ninety-one thousand, five hundred fifty-four".