21020061240 has 48 divisors (see below), whose sum is σ = 68315200200. Its totient is φ = 5605349568.

The previous prime is 21020061239. The next prime is 21020061287. The reversal of 21020061240 is 4216002012.

21020061240 is a `hidden beast` number, since 2 + 10 + 2 + 0 + 0 + 612 + 40 = 666.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29194170 + ... + 29194889.

Almost surely, 2^21020061240 is an apocalyptic number.

21020061240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21020061240 is an abundant number, since it is smaller than the sum of its proper divisors (47295138960).

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

21020061240 is a wasteful number, since it uses less digits than its factorization.

21020061240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58389076 (or 58389069 counting only the distinct ones).

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

Adding to 21020061240 its reverse (4216002012), we get a palindrome (25236063252).

The spelling of 21020061240 in words is "twenty-one billion, twenty million, sixty-one thousand, two hundred forty".