2151420221 has 4 divisors (see below), whose sum is σ = 2170459452. Its totient is φ = 2132380992.

The previous prime is 2151420209. The next prime is 2151420223. The reversal of 2151420221 is 1220241512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1044194596 + 1107225625 = 32314^2 + 33275^2 .

It is a cyclic number.

It is not a de Polignac number, because 2151420221 - 2³⁰ = 1077678397 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2151420193 and 2151420202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2151420223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9519446 + ... + 9519671.

It is an arithmetic number, because the mean of its divisors is an integer number (542614863).

Almost surely, 2^2151420221 is an apocalyptic number.

It is an amenable number.

2151420221 is a deficient number, since it is larger than the sum of its proper divisors (19039231).

2151420221 is a wasteful number, since it uses less digits than its factorization.

2151420221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19039230.

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 2151420221 is about 46383.4045861233. The cubic root of 2151420221 is about 1290.9470082806.

Adding to 2151420221 its reverse (1220241512), we get a palindrome (3371661733).

The spelling of 2151420221 in words is "two billion, one hundred fifty-one million, four hundred twenty thousand, two hundred twenty-one".