21456620546 has 4 divisors (see below), whose sum is σ = 32184930822. Its totient is φ = 10728310272.

The previous prime is 21456620513. The next prime is 21456620573. The reversal of 21456620546 is 64502665412.

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., 11019750625 + 10436869921 = 104975^2 + 102161^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5364155135 + ... + 5364155138.

Almost surely, 2^21456620546 is an apocalyptic number.

21456620546 is a deficient number, since it is larger than the sum of its proper divisors (10728310276).

21456620546 is a wasteful number, since it uses less digits than its factorization.

21456620546 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10728310275.

The product of its (nonzero) digits is 345600, while the sum is 41.

The spelling of 21456620546 in words is "twenty-one billion, four hundred fifty-six million, six hundred twenty thousand, five hundred forty-six".