21545680658 has 4 divisors (see below), whose sum is σ = 32318520990. Its totient is φ = 10772840328.

The previous prime is 21545680631. The next prime is 21545680679. The reversal of 21545680658 is 85608654512.

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

It can be written as a sum of positive squares in only one way, i.e., 20746657369 + 799023289 = 144037^2 + 28267^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5386420163 + ... + 5386420166.

Almost surely, 2^21545680658 is an apocalyptic number.

21545680658 is a deficient number, since it is larger than the sum of its proper divisors (10772840332).

21545680658 is a wasteful number, since it uses less digits than its factorization.

21545680658 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10772840331.

The product of its (nonzero) digits is 2304000, while the sum is 50.

The spelling of 21545680658 in words is "twenty-one billion, five hundred forty-five million, six hundred eighty thousand, six hundred fifty-eight".