157655821 has 2 divisors, whose sum is σ = 157655822. Its totient is φ = 157655820.

The previous prime is 157655791. The next prime is 157655843. The reversal of 157655821 is 128556751.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155900196 + 1755625 = 12486^2 + 1325^2 .

It is an emirp because it is prime and its reverse (128556751) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-157655821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (157655851) 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 as a sum of consecutive naturals, namely, 78827910 + 78827911.

It is an arithmetic number, because the mean of its divisors is an integer number (78827911).

Almost surely, 2^157655821 is an apocalyptic number.

It is an amenable number.

157655821 is a deficient number, since it is larger than the sum of its proper divisors (1).

157655821 is an equidigital number, since it uses as much as digits as its factorization.

157655821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 84000, while the sum is 40.

The square root of 157655821 is about 12556.1069205387. The cubic root of 157655821 is about 540.2191851409.

The spelling of 157655821 in words is "one hundred fifty-seven million, six hundred fifty-five thousand, eight hundred twenty-one".