21202120155 has 8 divisors (see below), whose sum is σ = 33923392272. Its totient is φ = 11307797408.

The previous prime is 21202120117. The next prime is 21202120183. The reversal of 21202120155 is 55102120212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21202120155 - 2⁶ = 21202120091 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 706737324 + ... + 706737353.

It is an arithmetic number, because the mean of its divisors is an integer number (4240424034).

Almost surely, 2^21202120155 is an apocalyptic number.

21202120155 is a deficient number, since it is larger than the sum of its proper divisors (12721272117).

21202120155 is a wasteful number, since it uses less digits than its factorization.

21202120155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1413474685.

The product of its (nonzero) digits is 400, while the sum is 21.

Adding to 21202120155 its reverse (55102120212), we get a palindrome (76304240367).

The spelling of 21202120155 in words is "twenty-one billion, two hundred two million, one hundred twenty thousand, one hundred fifty-five".