1213651 has 2 divisors, whose sum is σ = 1213652. Its totient is φ = 1213650.

The previous prime is 1213643. The next prime is 1213657. The reversal of 1213651 is 1563121.

1213651 = T₈₉₈ + T₈₉₉ + T₉₀₀.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1213651 - 2³ = 1213643 is a prime.

It is not a weakly prime, because it can be changed into another prime (1213657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 606825 + 606826.

It is an arithmetic number, because the mean of its divisors is an integer number (606826).

2^1213651 is an apocalyptic number.

1213651 is the 900-th centered triangular number.

1213651 is a deficient number, since it is larger than the sum of its proper divisors (1).

1213651 is an equidigital number, since it uses as much as digits as its factorization.

1213651 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 180, while the sum is 19.

The square root of 1213651 is about 1101.6582954800. The cubic root of 1213651 is about 106.6672927481.

Adding to 1213651 its reverse (1563121), we get a palindrome (2776772).

The spelling of 1213651 in words is "one million, two hundred thirteen thousand, six hundred fifty-one".