6521487021 has 72 divisors (see below), whose sum is σ = 11605711104. Its totient is φ = 3454747200.

The previous prime is 6521486987. The next prime is 6521487023. The reversal of 6521487021 is 1207841256.

6521487021 is a `hidden beast` number, since 6 + 521 + 48 + 70 + 21 = 666.

It is not a de Polignac number, because 6521487021 - 2²³ = 6513098413 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6521487023) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 1065871 + ... + 1071971.

It is an arithmetic number, because the mean of its divisors is an integer number (161190432).

Almost surely, 2^6521487021 is an apocalyptic number.

It is an amenable number.

6521487021 is a deficient number, since it is larger than the sum of its proper divisors (5084224083).

6521487021 is a wasteful number, since it uses less digits than its factorization.

6521487021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6199 (or 6177 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 36.

The square root of 6521487021 is about 80755.7243853338. The cubic root of 6521487021 is about 1868.3097408365.

The spelling of 6521487021 in words is "six billion, five hundred twenty-one million, four hundred eighty-seven thousand, twenty-one".