21390519447 has 48 divisors (see below), whose sum is σ = 36794459520. Its totient is φ = 12281608800.

The previous prime is 21390519389. The next prime is 21390519457. The reversal of 21390519447 is 74491509312.

21390519447 is a `hidden beast` number, since 2 + 1 + 3 + 90 + 519 + 4 + 47 = 666.

It is not a de Polignac number, because 21390519447 - 2⁸ = 21390519191 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21390519457) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 159804 + ... + 261377.

It is an arithmetic number, because the mean of its divisors is an integer number (766551240).

Almost surely, 2^21390519447 is an apocalyptic number.

21390519447 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

21390519447 is a deficient number, since it is larger than the sum of its proper divisors (15403940073).

21390519447 is a wasteful number, since it uses less digits than its factorization.

21390519447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 421226 (or 421214 counting only the distinct ones).

The product of its (nonzero) digits is 272160, while the sum is 45.

The spelling of 21390519447 in words is "twenty-one billion, three hundred ninety million, five hundred nineteen thousand, four hundred forty-seven".