1951821 has 12 divisors (see below), whose sum is σ = 2985372. Its totient is φ = 1224576.

The previous prime is 1951819. The next prime is 1951823. The reversal of 1951821 is 1281591.

It is an interprime number because it is at equal distance from previous prime (1951819) and next prime (1951823).

It can be written as a sum of positive squares in 2 ways, for example, as 1334025 + 617796 = 1155^2 + 786^2 .

It is not a de Polignac number, because 1951821 - 2¹ = 1951819 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1951823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6226 + ... + 6531.

It is an arithmetic number, because the mean of its divisors is an integer number (248781).

2^1951821 is an apocalyptic number.

It is an amenable number.

1951821 is a deficient number, since it is larger than the sum of its proper divisors (1033551).

1951821 is a wasteful number, since it uses less digits than its factorization.

1951821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12780 (or 12777 counting only the distinct ones).

The product of its digits is 720, while the sum is 27.

The square root of 1951821 is about 1397.0758748185. The cubic root of 1951821 is about 124.9721751400.

It can be divided in two parts, 1951 and 821, that added together give a palindrome (2772).

The spelling of 1951821 in words is "one million, nine hundred fifty-one thousand, eight hundred twenty-one".