21935958647 has 4 divisors (see below), whose sum is σ = 21976061496. Its totient is φ = 21895855800.

The previous prime is 21935958637. The next prime is 21935958673. The reversal of 21935958647 is 74685953912.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21935958647 - 2²² = 21931764343 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 (21935958607) 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, 20050604 + ... + 20051697.

It is an arithmetic number, because the mean of its divisors is an integer number (5494015374).

Almost surely, 2^21935958647 is an apocalyptic number.

21935958647 is a deficient number, since it is larger than the sum of its proper divisors (40102849).

21935958647 is an equidigital number, since it uses as much as digits as its factorization.

21935958647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40102848.

The product of its digits is 16329600, while the sum is 59.

The spelling of 21935958647 in words is "twenty-one billion, nine hundred thirty-five million, nine hundred fifty-eight thousand, six hundred forty-seven".