2151621 has 6 divisors (see below), whose sum is σ = 3107910. Its totient is φ = 1434408.

The previous prime is 2151619. The next prime is 2151623. The reversal of 2151621 is 1261512.

It is an interprime number because it is at equal distance from previous prime (2151619) and next prime (2151623).

It can be written as a sum of positive squares in only one way, i.e., 2117025 + 34596 = 1455^2 + 186^2 .

It is not a de Polignac number, because 2151621 - 2¹ = 2151619 is a prime.

2151621 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 2151594 and 2151603.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2151623) 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, 119526 + ... + 119543.

It is an arithmetic number, because the mean of its divisors is an integer number (517985).

2^2151621 is an apocalyptic number.

It is an amenable number.

2151621 is a deficient number, since it is larger than the sum of its proper divisors (956289).

2151621 is a wasteful number, since it uses less digits than its factorization.

2151621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 239075 (or 239072 counting only the distinct ones).

The product of its digits is 120, while the sum is 18.

The square root of 2151621 is about 1466.8404821248. The cubic root of 2151621 is about 129.0987165783.

It can be divided in two parts, 2151 and 621, that added together give a palindrome (2772).

The spelling of 2151621 in words is "two million, one hundred fifty-one thousand, six hundred twenty-one".