1620551 has 2 divisors, whose sum is σ = 1620552. Its totient is φ = 1620550.

The previous prime is 1620547. The next prime is 1620569. The reversal of 1620551 is 1550261.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1620551 - 2² = 1620547 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1620571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810275 + 810276.

It is an arithmetic number, because the mean of its divisors is an integer number (810276).

2^1620551 is an apocalyptic number.

1620551 is a deficient number, since it is larger than the sum of its proper divisors (1).

1620551 is an equidigital number, since it uses as much as digits as its factorization.

1620551 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 1620551 is about 1273.0086409762. The cubic root of 1620551 is about 117.4593431089.

The spelling of 1620551 in words is "one million, six hundred twenty thousand, five hundred fifty-one".