157721407 has 2 divisors, whose sum is σ = 157721408. Its totient is φ = 157721406.

The previous prime is 157721357. The next prime is 157721411. The reversal of 157721407 is 704127751.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 157721407 - 2¹⁹ = 157197119 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (157721467) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 78860703 + 78860704.

It is an arithmetic number, because the mean of its divisors is an integer number (78860704).

Almost surely, 2^157721407 is an apocalyptic number.

157721407 is a deficient number, since it is larger than the sum of its proper divisors (1).

157721407 is an equidigital number, since it uses as much as digits as its factorization.

157721407 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13720, while the sum is 34.

The square root of 157721407 is about 12558.7183661391. The cubic root of 157721407 is about 540.2940864950.

The spelling of 157721407 in words is "one hundred fifty-seven million, seven hundred twenty-one thousand, four hundred seven".