157087721 has 4 divisors (see below), whose sum is σ = 179528832. Its totient is φ = 134646612.

The previous prime is 157087703. The next prime is 157087747. The reversal of 157087721 is 127780751.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 157087721 - 2²² = 152893417 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (157087781) 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, 11220545 + ... + 11220558.

It is an arithmetic number, because the mean of its divisors is an integer number (44882208).

Almost surely, 2^157087721 is an apocalyptic number.

It is an amenable number.

157087721 is a deficient number, since it is larger than the sum of its proper divisors (22441111).

157087721 is an equidigital number, since it uses as much as digits as its factorization.

157087721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22441110.

The product of its (nonzero) digits is 27440, while the sum is 38.

The square root of 157087721 is about 12533.4640463042. The cubic root of 157087721 is about 539.5695254690.

The spelling of 157087721 in words is "one hundred fifty-seven million, eighty-seven thousand, seven hundred twenty-one".