100721506 has 4 divisors (see below), whose sum is σ = 151082262. Its totient is φ = 50360752.

The previous prime is 100721503. The next prime is 100721507. The reversal of 100721506 is 605127001.

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., 60918025 + 39803481 = 7805^2 + 6309^2 .

It is a super-3 number, since 3×100721506³ (a number of 25 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (100721501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25180375 + ... + 25180378.

Almost surely, 2^100721506 is an apocalyptic number.

100721506 is a deficient number, since it is larger than the sum of its proper divisors (50360756).

100721506 is an equidigital number, since it uses as much as digits as its factorization.

100721506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50360755.

The product of its (nonzero) digits is 420, while the sum is 22.

The square root of 100721506 is about 10036.0104623301. The cubic root of 100721506 is about 465.2725207177.

Adding to 100721506 its reverse (605127001), we get a palindrome (705848507).

The spelling of 100721506 in words is "one hundred million, seven hundred twenty-one thousand, five hundred six".