21261485744648 has 36 divisors (see below), whose sum is σ = 40266394214535. Its totient is φ = 10524835896000.

The previous prime is 21261485744641. The next prime is 21261485744659. The reversal of 21261485744648 is 84644758416212.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 5 ways, for example, as 19500190473604 + 1761295271044 = 4415902^2 + 1327138^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=3260482.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21261485744641) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1317226658 + ... + 1317242798.

Almost surely, 2^{21261485744648} is an apocalyptic number.

It is an amenable number.

21261485744648 is a deficient number, since it is larger than the sum of its proper divisors (19004908469887).

21261485744648 is an frugal number, since it uses more digits than its factorization.

21261485744648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32490 (or 16244 counting only the distinct ones).

The product of its digits is 82575360, while the sum is 62.

The spelling of 21261485744648 in words is "twenty-one trillion, two hundred sixty-one billion, four hundred eighty-five million, seven hundred forty-four thousand, six hundred forty-eight".