1621541 has 2 divisors, whose sum is σ = 1621542. Its totient is φ = 1621540.

The previous prime is 1621537. The next prime is 1621559. The reversal of 1621541 is 1451261.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1600225 + 21316 = 1265^2 + 146^2 .

It is a cyclic number.

It is not a de Polignac number, because 1621541 - 2² = 1621537 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1621141) 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, 810770 + 810771.

It is an arithmetic number, because the mean of its divisors is an integer number (810771).

2^1621541 is an apocalyptic number.

It is an amenable number.

1621541 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621541 is an equidigital number, since it uses as much as digits as its factorization.

1621541 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 240, while the sum is 20.

The square root of 1621541 is about 1273.3974242160. The cubic root of 1621541 is about 117.4832570077.

The spelling of 1621541 in words is "one million, six hundred twenty-one thousand, five hundred forty-one".