1621921 has 8 divisors (see below), whose sum is σ = 1862784. Its totient is φ = 1383360.

The previous prime is 1621909. The next prime is 1621931. The reversal of 1621921 is 1291261.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1621921 - 2⁷ = 1621793 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1621892 and 1621901.

It is not an unprimeable number, because it can be changed into a prime (1621931) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1401 + ... + 2281.

It is an arithmetic number, because the mean of its divisors is an integer number (232848).

2^1621921 is an apocalyptic number.

It is an amenable number.

1621921 is a deficient number, since it is larger than the sum of its proper divisors (240863).

1621921 is an equidigital number, since it uses as much as digits as its factorization.

1621921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1151.

The product of its digits is 216, while the sum is 22.

The square root of 1621921 is about 1273.5466226252. The cubic root of 1621921 is about 117.4924334950.

It can be divided in two parts, 1621 and 921, that multiplied together give a palindrome (1492941).

The spelling of 1621921 in words is "one million, six hundred twenty-one thousand, nine hundred twenty-one".