2545904256921 has 9 divisors (see below), whose sum is σ = 3677424174229. Its totient is φ = 1697266313436.

The previous prime is 2545904256881. The next prime is 2545904256977. The reversal of 2545904256921 is 1296524095452.

The square root of 2545904256921 is 1595589.

It is a perfect power (a square), and thus also a powerful number.

2545904256921 is a `hidden beast` number, since 2 + 5 + 4 + 59 + 0 + 4 + 2 + 569 + 21 = 666.

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 2545904256921 - 2⁹ = 2545904256409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2545904256121) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 4520836 + ... + 5052698.

Almost surely, 2^{2545904256921} is an apocalyptic number.

2545904256921 is the 1595589-th square number.

2545904256921 is the 797795-th centered octagonal number.

It is an amenable number.

2545904256921 is a deficient number, since it is larger than the sum of its proper divisors (1131519917308).

2545904256921 is an frugal number, since it uses more digits than its factorization.

2545904256921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1063732 (or 531866 counting only the distinct ones).

The product of its (nonzero) digits is 7776000, while the sum is 54.

The spelling of 2545904256921 in words is "two trillion, five hundred forty-five billion, nine hundred four million, two hundred fifty-six thousand, nine hundred twenty-one".