157771981 has 4 divisors (see below), whose sum is σ = 158573052. Its totient is φ = 156970912.

The previous prime is 157771963. The next prime is 157771987. The reversal of 157771981 is 189177751.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 72505225 + 85266756 = 8515^2 + 9234^2 .

It is a cyclic number.

It is not a de Polignac number, because 157771981 - 2¹³ = 157763789 is a prime.

It is a super-2 number, since 2×157771981² = 49783995977328722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (157771987) 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, 400240 + ... + 400633.

It is an arithmetic number, because the mean of its divisors is an integer number (39643263).

Almost surely, 2^157771981 is an apocalyptic number.

It is an amenable number.

157771981 is a deficient number, since it is larger than the sum of its proper divisors (801071).

157771981 is an equidigital number, since it uses as much as digits as its factorization.

157771981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 801070.

The product of its digits is 123480, while the sum is 46.

The square root of 157771981 is about 12560.7317063935. The cubic root of 157771981 is about 540.3518294769.

The spelling of 157771981 in words is "one hundred fifty-seven million, seven hundred seventy-one thousand, nine hundred eighty-one".