1861621 has 2 divisors, whose sum is σ = 1861622. Its totient is φ = 1861620.

The previous prime is 1861591. The next prime is 1861631. The reversal of 1861621 is 1261681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1199025 + 662596 = 1095^2 + 814^2 .

It is a cyclic number.

It is not a de Polignac number, because 1861621 - 2⁵ = 1861589 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1861631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 930810 + 930811.

It is an arithmetic number, because the mean of its divisors is an integer number (930811).

2^1861621 is an apocalyptic number.

It is an amenable number.

1861621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1861621 is an equidigital number, since it uses as much as digits as its factorization.

1861621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 576, while the sum is 25.

The square root of 1861621 is about 1364.4123277074. The cubic root of 1861621 is about 123.0166104432.

The spelling of 1861621 in words is "one million, eight hundred sixty-one thousand, six hundred twenty-one".