1621979 has 2 divisors, whose sum is σ = 1621980. Its totient is φ = 1621978.

The previous prime is 1621933. The next prime is 1621993. The reversal of 1621979 is 9791261.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1621979 - 2⁸ = 1621723 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1621909) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810989 + 810990.

It is an arithmetic number, because the mean of its divisors is an integer number (810990).

2^1621979 is an apocalyptic number.

1621979 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621979 is an equidigital number, since it uses as much as digits as its factorization.

1621979 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6804, while the sum is 35.

The square root of 1621979 is about 1273.5693934765. The cubic root of 1621979 is about 117.4938339906.

The spelling of 1621979 in words is "one million, six hundred twenty-one thousand, nine hundred seventy-nine".