155930921 has 2 divisors, whose sum is σ = 155930922. Its totient is φ = 155930920.

The previous prime is 155930903. The next prime is 155930933. The reversal of 155930921 is 129039551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155875225 + 55696 = 12485^2 + 236^2 .

It is an emirp because it is prime and its reverse (129039551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 155930921 - 2¹⁴ = 155914537 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (155930221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77965460 + 77965461.

It is an arithmetic number, because the mean of its divisors is an integer number (77965461).

Almost surely, 2^155930921 is an apocalyptic number.

It is an amenable number.

155930921 is a deficient number, since it is larger than the sum of its proper divisors (1).

155930921 is an equidigital number, since it uses as much as digits as its factorization.

155930921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12150, while the sum is 35.

The square root of 155930921 is about 12487.2303174083. The cubic root of 155930921 is about 538.2417907286.

The spelling of 155930921 in words is "one hundred fifty-five million, nine hundred thirty thousand, nine hundred twenty-one".