21865991457 has 8 divisors (see below), whose sum is σ = 29227361760. Its totient is φ = 14540974400.

The previous prime is 21865991443. The next prime is 21865991471. The reversal of 21865991457 is 75419956812.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21865991443) and next prime (21865991471).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21865991457 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21865991397 and 21865991406.

It is not an unprimeable number, because it can be changed into a prime (21865996457) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9086907 + ... + 9089312.

It is an arithmetic number, because the mean of its divisors is an integer number (3653420220).

Almost surely, 2^21865991457 is an apocalyptic number.

It is an amenable number.

21865991457 is a deficient number, since it is larger than the sum of its proper divisors (7361370303).

21865991457 is a wasteful number, since it uses less digits than its factorization.

21865991457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18176623.

The product of its digits is 5443200, while the sum is 57.

The spelling of 21865991457 in words is "twenty-one billion, eight hundred sixty-five million, nine hundred ninety-one thousand, four hundred fifty-seven".