106217721 has 6 divisors (see below), whose sum is σ = 153425610. Its totient is φ = 70811808.

The previous prime is 106217707. The next prime is 106217729. The reversal of 106217721 is 127712601.

106217721 is a `hidden beast` number, since 10 + 621 + 7 + 7 + 21 = 666.

It can be written as a sum of positive squares in only one way, i.e., 90725625 + 15492096 = 9525^2 + 3936^2 .

It is not a de Polignac number, because 106217721 - 2²⁵ = 72663289 is a prime.

It is a super-2 number, since 2×106217721² = 22564408508867682, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (106217729) 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 5 ways as a sum of consecutive naturals, for example, 5900976 + ... + 5900993.

It is an arithmetic number, because the mean of its divisors is an integer number (25570935).

Almost surely, 2^106217721 is an apocalyptic number.

It is an amenable number.

106217721 is a deficient number, since it is larger than the sum of its proper divisors (47207889).

106217721 is a wasteful number, since it uses less digits than its factorization.

106217721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11801975 (or 11801972 counting only the distinct ones).

The product of its (nonzero) digits is 1176, while the sum is 27.

The square root of 106217721 is about 10306.1981836175. The cubic root of 106217721 is about 473.5861500151.

The spelling of 106217721 in words is "one hundred six million, two hundred seventeen thousand, seven hundred twenty-one".