155021939 has 4 divisors (see below), whose sum is σ = 156153624. Its totient is φ = 153890256.

The previous prime is 155021899. The next prime is 155021947. The reversal of 155021939 is 939120551.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 939120551 = 1699 ⋅552749.

It is a cyclic number.

It is not a de Polignac number, because 155021939 - 2⁸ = 155021683 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 155021899 and 155021908.

It is not an unprimeable number, because it can be changed into a prime (155020939) 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, 565637 + ... + 565910.

It is an arithmetic number, because the mean of its divisors is an integer number (39038406).

Almost surely, 2^155021939 is an apocalyptic number.

155021939 is a deficient number, since it is larger than the sum of its proper divisors (1131685).

155021939 is a wasteful number, since it uses less digits than its factorization.

155021939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1131684.

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

The square root of 155021939 is about 12450.7806582559. The cubic root of 155021939 is about 537.1938782569.

The spelling of 155021939 in words is "one hundred fifty-five million, twenty-one thousand, nine hundred thirty-nine".