2145540021 has 8 divisors (see below), whose sum is σ = 3011284320. Its totient is φ = 1355077872.

The previous prime is 2145539987. The next prime is 2145540043. The reversal of 2145540021 is 1200455412.

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

It is a de Polignac number, because none of the positive numbers 2^k-2145540021 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 2145539973 and 2145540000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2145540091) 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, 18820470 + ... + 18820583.

It is an arithmetic number, because the mean of its divisors is an integer number (376410540).

Almost surely, 2^2145540021 is an apocalyptic number.

It is an amenable number.

2145540021 is a deficient number, since it is larger than the sum of its proper divisors (865744299).

2145540021 is a wasteful number, since it uses less digits than its factorization.

2145540021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37641075.

The product of its (nonzero) digits is 1600, while the sum is 24.

The square root of 2145540021 is about 46319.9743199411. The cubic root of 2145540021 is about 1289.7698086951.

Adding to 2145540021 its reverse (1200455412), we get a palindrome (3345995433).

The spelling of 2145540021 in words is "two billion, one hundred forty-five million, five hundred forty thousand, twenty-one".