155878621 has 2 divisors, whose sum is σ = 155878622. Its totient is φ = 155878620.

The previous prime is 155878609. The next prime is 155878651. The reversal of 155878621 is 126878551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 136562596 + 19316025 = 11686^2 + 4395^2 .

It is an emirp because it is prime and its reverse (126878551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 155878621 - 2⁵ = 155878589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155878601) 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, 77939310 + 77939311.

It is an arithmetic number, because the mean of its divisors is an integer number (77939311).

Almost surely, 2^155878621 is an apocalyptic number.

It is an amenable number.

155878621 is a deficient number, since it is larger than the sum of its proper divisors (1).

155878621 is an equidigital number, since it uses as much as digits as its factorization.

155878621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 134400, while the sum is 43.

The square root of 155878621 is about 12485.1360024631. The cubic root of 155878621 is about 538.1816076824.

The spelling of 155878621 in words is "one hundred fifty-five million, eight hundred seventy-eight thousand, six hundred twenty-one".