1216401961 has 2 divisors, whose sum is σ = 1216401962. Its totient is φ = 1216401960.

The previous prime is 1216401937. The next prime is 1216402009. The reversal of 1216401961 is 1691046121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 970696336 + 245705625 = 31156^2 + 15675^2 .

It is a cyclic number.

It is not a de Polignac number, because 1216401961 - 2⁹ = 1216401449 is a prime.

It is not a weakly prime, because it can be changed into another prime (1216407961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 608200980 + 608200981.

It is an arithmetic number, because the mean of its divisors is an integer number (608200981).

Almost surely, 2^1216401961 is an apocalyptic number.

It is an amenable number.

1216401961 is a deficient number, since it is larger than the sum of its proper divisors (1).

1216401961 is an equidigital number, since it uses as much as digits as its factorization.

1216401961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 1216401961 is about 34876.9545832201. The cubic root of 1216401961 is about 1067.4782554571.

The spelling of 1216401961 in words is "one billion, two hundred sixteen million, four hundred one thousand, nine hundred sixty-one".