1621973 has 6 divisors (see below), whose sum is σ = 1712214. Its totient is φ = 1536264.

The previous prime is 1621933. The next prime is 1621979. The reversal of 1621973 is 3791261.

It can be written as a sum of positive squares in only one way, i.e., 1620529 + 1444 = 1273^2 + 38^2 .

It is not a de Polignac number, because 1621973 - 2⁶ = 1621909 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1621979) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1886 + ... + 2607.

It is an arithmetic number, because the mean of its divisors is an integer number (285369).

2^1621973 is an apocalyptic number.

It is an amenable number.

1621973 is a deficient number, since it is larger than the sum of its proper divisors (90241).

1621973 is an equidigital number, since it uses as much as digits as its factorization.

1621973 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4531 (or 4512 counting only the distinct ones).

The product of its digits is 2268, while the sum is 29.

The square root of 1621973 is about 1273.5670378900. The cubic root of 1621973 is about 117.4936891133.

It can be divided in two parts, 162197 and 3, that multiplied together give a triangular number (486591 = T₉₈₆).

The spelling of 1621973 in words is "one million, six hundred twenty-one thousand, nine hundred seventy-three".