21420553664 has 28 divisors (see below), whose sum is σ = 42516119184. Its totient is φ = 10707830784.

The previous prime is 21420553663. The next prime is 21420553703. The reversal of 21420553664 is 46635502412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21420553663) 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, 262544 + ... + 334320.

It is an arithmetic number, because the mean of its divisors is an integer number (1518432828).

Almost surely, 2^21420553664 is an apocalyptic number.

It is an amenable number.

21420553664 is a deficient number, since it is larger than the sum of its proper divisors (21095565520).

21420553664 is an equidigital number, since it uses as much as digits as its factorization.

21420553664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76452 (or 76442 counting only the distinct ones).

The product of its (nonzero) digits is 172800, while the sum is 38.

The spelling of 21420553664 in words is "twenty-one billion, four hundred twenty million, five hundred fifty-three thousand, six hundred sixty-four".