1978211307121 has 9 divisors (see below), whose sum is σ = 2301196034649. Its totient is φ = 1695601252884.

The previous prime is 1978211307091. The next prime is 1978211307133. The reversal of 1978211307121 is 1217031128791.

The square root of 1978211307121 is 1406489.

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

It is not a de Polignac number, because 1978211307121 - 2¹⁵ = 1978211274353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1978211307161) 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, 9744960 + ... + 9945886.

Almost surely, 2^{1978211307121} is an apocalyptic number.

1978211307121 is the 1406489-th square number.

1978211307121 is the 703245-th centered octagonal number.

It is an amenable number.

1978211307121 is a deficient number, since it is larger than the sum of its proper divisors (322984727528).

1978211307121 is an frugal number, since it uses more digits than its factorization.

1978211307121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 401868 (or 200934 counting only the distinct ones).

The product of its (nonzero) digits is 42336, while the sum is 43.

The spelling of 1978211307121 in words is "one trillion, nine hundred seventy-eight billion, two hundred eleven million, three hundred seven thousand, one hundred twenty-one".