21205533140 has 36 divisors (see below), whose sum is σ = 48947984148. Its totient is φ = 7711102080.

The previous prime is 21205533109. The next prime is 21205533143. The reversal of 21205533140 is 4133550212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 15064616644 + 6140916496 = 122738^2 + 78364^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21205533143) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4378889 + ... + 4383728.

Almost surely, 2^21205533140 is an apocalyptic number.

21205533140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21205533140 is an abundant number, since it is smaller than the sum of its proper divisors (27742451008).

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

21205533140 is a wasteful number, since it uses less digits than its factorization.

21205533140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8762648 (or 8762635 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 26.

The spelling of 21205533140 in words is "twenty-one billion, two hundred five million, five hundred thirty-three thousand, one hundred forty".