4021551 has 6 divisors (see below), whose sum is σ = 5808920. Its totient is φ = 2681028.

The previous prime is 4021543. The next prime is 4021561. The reversal of 4021551 is 1551204.

It is not a de Polignac number, because 4021551 - 2³ = 4021543 is a prime.

It is a Duffinian number.

4021551 is a lucky number.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (4021531) 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, 223411 + ... + 223428.

Almost surely, 2^4021551 is an apocalyptic number.

4021551 is a deficient number, since it is larger than the sum of its proper divisors (1787369).

4021551 is a wasteful number, since it uses less digits than its factorization.

4021551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 446845 (or 446842 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 4021551 is about 2005.3805125213. The cubic root of 4021551 is about 159.0246787373.

Adding to 4021551 its reverse (1551204), we get a palindrome (5572755).

It can be divided in two parts, 402 and 1551, that added together give a triangular number (1953 = T₆₂).

The spelling of 4021551 in words is "four million, twenty-one thousand, five hundred fifty-one".