21000736464 has 80 divisors (see below), whose sum is σ = 55797053760. Its totient is φ = 6801408000.

The previous prime is 21000736451. The next prime is 21000736469. The reversal of 21000736464 is 46463700012.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000736469) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1304464 + ... + 1320464.

It is an arithmetic number, because the mean of its divisors is an integer number (697463172).

Almost surely, 2^21000736464 is an apocalyptic number.

21000736464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21000736464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27898526880).

21000736464 is an abundant number, since it is smaller than the sum of its proper divisors (34796317296).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21000736464 is a wasteful number, since it uses less digits than its factorization.

21000736464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16788 (or 16782 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 33.

The spelling of 21000736464 in words is "twenty-one billion, seven hundred thirty-six thousand, four hundred sixty-four".