155621 has 2 divisors, whose sum is σ = 155622. Its totient is φ = 155620.
The previous prime is 155609. The next prime is 155627. The reversal of 155621 is 126551.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 148225 + 7396 = 385^2 + 86^2 .
It is an emirp because it is prime and its reverse (126551) is a distict prime.
It is a cyclic number.
It is not a de Polignac number, because 155621 - 26 = 155557 is a prime.
It is a Chen prime.
It is a plaindrome in base 13.
It is a junction number, because it is equal to n+sod(n) for n = 155593 and 155602.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (155627) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77810 + 77811.
It is an arithmetic number, because the mean of its divisors is an integer number (77811).
2155621 is an apocalyptic number.
It is an amenable number.
155621 is a deficient number, since it is larger than the sum of its proper divisors (1).
155621 is an equidigital number, since it uses as much as digits as its factorization.
155621 is an evil number, because the sum of its binary digits is even.
The product of its digits is 300, while the sum is 20.
The square root of 155621 is about 394.4882761249. The cubic root of 155621 is about 53.7884959487.
The spelling of 155621 in words is "one hundred fifty-five thousand, six hundred twenty-one".
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