157787721 has 96 divisors (see below), whose sum is σ = 297443328. Its totient is φ = 78382080.

The previous prime is 157787717. The next prime is 157787759. The reversal of 157787721 is 127787751.

It is a happy number.

157787721 is a `hidden beast` number, since 1 + 577 + 8 + 7 + 72 + 1 = 666.

157787721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 157787721 - 2² = 157787717 is a prime.

It is not an unprimeable number, because it can be changed into a prime (157787711) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1242360 + ... + 1242486.

It is an arithmetic number, because the mean of its divisors is an integer number (3098368).

Almost surely, 2^157787721 is an apocalyptic number.

It is an amenable number.

157787721 is a deficient number, since it is larger than the sum of its proper divisors (139655607).

157787721 is a wasteful number, since it uses less digits than its factorization.

157787721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 231 (or 228 counting only the distinct ones).

The product of its digits is 192080, while the sum is 45.

The square root of 157787721 is about 12561.3582466229. The cubic root of 157787721 is about 540.3697981405.

It can be divided in two parts, 1577 and 87721, that added together give a palindrome (89298).

The spelling of 157787721 in words is "one hundred fifty-seven million, seven hundred eighty-seven thousand, seven hundred twenty-one".