21390647375 has 16 divisors (see below), whose sum is σ = 28265855904. Its totient is φ = 16105897600.

The previous prime is 21390647371. The next prime is 21390647389. The reversal of 21390647375 is 57374609312.

It is not a de Polignac number, because 21390647375 - 2² = 21390647371 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21390647371) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5030969 + ... + 5035218.

It is an arithmetic number, because the mean of its divisors is an integer number (1766615994).

Almost surely, 2^21390647375 is an apocalyptic number.

21390647375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21390647375 is a deficient number, since it is larger than the sum of its proper divisors (6875208529).

21390647375 is a wasteful number, since it uses less digits than its factorization.

21390647375 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10066219 (or 10066209 counting only the distinct ones).

The product of its (nonzero) digits is 952560, while the sum is 47.

The spelling of 21390647375 in words is "twenty-one billion, three hundred ninety million, six hundred forty-seven thousand, three hundred seventy-five".