157721057 has 8 divisors (see below), whose sum is σ = 173058984. Its totient is φ = 142841088.

The previous prime is 157721041. The next prime is 157721077. The reversal of 157721057 is 750127751.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 43573201 + 114147856 = 6601^2 + 10684^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 157721057 - 2⁴ = 157721041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (157721027) 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 7 ways as a sum of consecutive naturals, for example, 113768 + ... + 115145.

It is an arithmetic number, because the mean of its divisors is an integer number (21632373).

Almost surely, 2^157721057 is an apocalyptic number.

It is an amenable number.

157721057 is a deficient number, since it is larger than the sum of its proper divisors (15337927).

157721057 is a wasteful number, since it uses less digits than its factorization.

157721057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 228979.

The product of its (nonzero) digits is 17150, while the sum is 35.

The square root of 157721057 is about 12558.7044315885. The cubic root of 157721057 is about 540.2936868387.

The spelling of 157721057 in words is "one hundred fifty-seven million, seven hundred twenty-one thousand, fifty-seven".