121773779521 has 9 divisors (see below), whose sum is σ = 122638636449. Its totient is φ = 120914986500.

The previous prime is 121773779509. The next prime is 121773779537. The reversal of 121773779521 is 125977377121.

The square root of 121773779521 is 348961.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 121773779521 - 2¹⁵ = 121773746753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121773779581) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 52691956 + ... + 52694266.

It is an arithmetic number, because the mean of its divisors is an integer number (13626515161).

Almost surely, 2^121773779521 is an apocalyptic number.

121773779521 is the 348961-st square number.

121773779521 is the 174481-st centered octagonal number.

It is an amenable number.

121773779521 is a deficient number, since it is larger than the sum of its proper divisors (864856928).

121773779521 is an frugal number, since it uses more digits than its factorization.

121773779521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4924 (or 2462 counting only the distinct ones).

The product of its digits is 1296540, while the sum is 52.

The spelling of 121773779521 in words is "one hundred twenty-one billion, seven hundred seventy-three million, seven hundred seventy-nine thousand, five hundred twenty-one".