1685221451 has 2 divisors, whose sum is σ = 1685221452. Its totient is φ = 1685221450.

The previous prime is 1685221427. The next prime is 1685221463. The reversal of 1685221451 is 1541225861.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1685221451 - 2⁶ = 1685221387 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (1685221151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 842610725 + 842610726.

It is an arithmetic number, because the mean of its divisors is an integer number (842610726).

Almost surely, 2^1685221451 is an apocalyptic number.

1685221451 is a deficient number, since it is larger than the sum of its proper divisors (1).

1685221451 is an equidigital number, since it uses as much as digits as its factorization.

1685221451 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19200, while the sum is 35.

The square root of 1685221451 is about 41051.4488294871. The cubic root of 1685221451 is about 1190.0147000514.

The spelling of 1685221451 in words is "one billion, six hundred eighty-five million, two hundred twenty-one thousand, four hundred fifty-one".