100721551 has 4 divisors (see below), whose sum is σ = 115110352. Its totient is φ = 86332752.

The previous prime is 100721539. The next prime is 100721557. The reversal of 100721551 is 155127001.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 155127001 = 19 ⋅8164579.

It is a cyclic number.

It is not a de Polignac number, because 100721551 - 2¹³ = 100713359 is a prime.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (100721557) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7194390 + ... + 7194403.

It is an arithmetic number, because the mean of its divisors is an integer number (28777588).

Almost surely, 2^100721551 is an apocalyptic number.

100721551 is a deficient number, since it is larger than the sum of its proper divisors (14388801).

100721551 is an equidigital number, since it uses as much as digits as its factorization.

100721551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14388800.

The product of its (nonzero) digits is 350, while the sum is 22.

The square root of 100721551 is about 10036.0127042566. The cubic root of 100721551 is about 465.2725900086.

Adding to 100721551 its reverse (155127001), we get a palindrome (255848552).

The spelling of 100721551 in words is "one hundred million, seven hundred twenty-one thousand, five hundred fifty-one".