21010321440 has 72 divisors (see below), whose sum is σ = 71697726828. Its totient is φ = 5602752000.

The previous prime is 21010321421. The next prime is 21010321457. The reversal of 21010321440 is 4412301012.

21010321440 is a `hidden beast` number, since 210 + 10 + 3 + 2 + 1 + 440 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 17118058896 + 3892262544 = 130836^2 + 62388^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7293811 + ... + 7296690.

Almost surely, 2^21010321440 is an apocalyptic number.

21010321440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21010321440 is an abundant number, since it is smaller than the sum of its proper divisors (50687405388).

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

21010321440 is a wasteful number, since it uses less digits than its factorization.

21010321440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14590522 (or 14590511 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

Adding to 21010321440 its reverse (4412301012), we get a palindrome (25422622452).

The spelling of 21010321440 in words is "twenty-one billion, ten million, three hundred twenty-one thousand, four hundred forty".