2521201621 has 4 divisors (see below), whose sum is σ = 2521325772. Its totient is φ = 2521077472.

The previous prime is 2521201607. The next prime is 2521201663. The reversal of 2521201621 is 1261021252.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 225450225 + 2295751396 = 15015^2 + 47914^2 .

It is a cyclic number.

It is not a de Polignac number, because 2521201621 - 2⁷ = 2521201493 is a prime.

It is a super-2 number, since 2×2521201621² = 12712915227466055282, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2521201592 and 2521201601.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2521201691) 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, 23710 + ... + 74863.

It is an arithmetic number, because the mean of its divisors is an integer number (630331443).

Almost surely, 2^2521201621 is an apocalyptic number.

It is an amenable number.

2521201621 is a deficient number, since it is larger than the sum of its proper divisors (124151).

2521201621 is an equidigital number, since it uses as much as digits as its factorization.

2521201621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124150.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 2521201621 is about 50211.5685972864. The cubic root of 2521201621 is about 1361.0346835292.

Adding to 2521201621 its reverse (1261021252), we get a palindrome (3782222873).

The spelling of 2521201621 in words is "two billion, five hundred twenty-one million, two hundred one thousand, six hundred twenty-one".