1901621 has 4 divisors (see below), whose sum is σ = 1948044. Its totient is φ = 1855200.

The previous prime is 1901597. The next prime is 1901639. The reversal of 1901621 is 1261091.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1261091 = 13 ⋅97007.

It can be written as a sum of positive squares in 2 ways, for example, as 579121 + 1322500 = 761^2 + 1150^2 .

It is a cyclic number.

It is not a de Polignac number, because 1901621 - 2¹⁰ = 1900597 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1901593 and 1901602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1901651) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23150 + ... + 23231.

It is an arithmetic number, because the mean of its divisors is an integer number (487011).

2^1901621 is an apocalyptic number.

It is an amenable number.

1901621 is a deficient number, since it is larger than the sum of its proper divisors (46423).

1901621 is an equidigital number, since it uses as much as digits as its factorization.

1901621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46422.

The product of its (nonzero) digits is 108, while the sum is 20.

The square root of 1901621 is about 1378.9927483493. The cubic root of 1901621 is about 123.8914459252.

Adding to 1901621 its sum of digits (20), we get a square (1901641 = 1379²).

The spelling of 1901621 in words is "one million, nine hundred one thousand, six hundred twenty-one".