1211761655 has 16 divisors (see below), whose sum is σ = 1608295584. Its totient is φ = 870652800.

The previous prime is 1211761633. The next prime is 1211761657. The reversal of 1211761655 is 5561671121.

It is not a de Polignac number, because 1211761655 - 2⁶ = 1211761591 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1211761657) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 249521 + ... + 254330.

It is an arithmetic number, because the mean of its divisors is an integer number (100518474).

Almost surely, 2^1211761655 is an apocalyptic number.

1211761655 is a deficient number, since it is larger than the sum of its proper divisors (396533929).

1211761655 is a wasteful number, since it uses less digits than its factorization.

1211761655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 503906.

The product of its digits is 12600, while the sum is 35.

The square root of 1211761655 is about 34810.3670621268. The cubic root of 1211761655 is about 1066.1191274608.

The spelling of 1211761655 in words is "one billion, two hundred eleven million, seven hundred sixty-one thousand, six hundred fifty-five".