1643552421 has 64 divisors (see below), whose sum is σ = 2689873920. Its totient is φ = 871879680.

The previous prime is 1643552387. The next prime is 1643552429. The reversal of 1643552421 is 1242553461.

It is not a de Polignac number, because 1643552421 - 2¹³ = 1643544229 is a prime.

It is a super-2 number, since 2×1643552421² = 5402529121149922482, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1643552429) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 5848801 + ... + 5849081.

It is an arithmetic number, because the mean of its divisors is an integer number (42029280).

Almost surely, 2^1643552421 is an apocalyptic number.

It is an amenable number.

1643552421 is a deficient number, since it is larger than the sum of its proper divisors (1046321499).

1643552421 is a wasteful number, since it uses less digits than its factorization.

1643552421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 554.

The product of its digits is 28800, while the sum is 33.

The square root of 1643552421 is about 40540.7501287285. The cubic root of 1643552421 is about 1180.1245729347.

The spelling of 1643552421 in words is "one billion, six hundred forty-three million, five hundred fifty-two thousand, four hundred twenty-one".