2151531021 has 8 divisors (see below), whose sum is σ = 2993434560. Its totient is φ = 1371990752.

The previous prime is 2151530981. The next prime is 2151531023. The reversal of 2151531021 is 1201351512.

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

It is a cyclic number.

It is not a de Polignac number, because 2151531021 - 2⁶ = 2151530957 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2151531023) 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, 15590736 + ... + 15590873.

It is an arithmetic number, because the mean of its divisors is an integer number (374179320).

Almost surely, 2^2151531021 is an apocalyptic number.

It is an amenable number.

2151531021 is a deficient number, since it is larger than the sum of its proper divisors (841903539).

2151531021 is a wasteful number, since it uses less digits than its factorization.

2151531021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31181635.

The product of its (nonzero) digits is 300, while the sum is 21.

The square root of 2151531021 is about 46384.5989634491. The cubic root of 2151531021 is about 1290.9691695289.

Adding to 2151531021 its reverse (1201351512), we get a palindrome (3352882533).

The spelling of 2151531021 in words is "two billion, one hundred fifty-one million, five hundred thirty-one thousand, twenty-one".