21121962840 has 512 divisors, whose sum is σ = 80356147200. Its totient is φ = 4888512000.

The previous prime is 21121962811. The next prime is 21121962847. The reversal of 21121962840 is 4826912112.

21121962840 is a `hidden beast` number, since 2 + 1 + 1 + 21 + 9 + 628 + 4 + 0 = 666.

It is a super-2 number, since 2×21121962840² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21121962795 and 21121962804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121962847) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 30566895 + ... + 30567585.

It is an arithmetic number, because the mean of its divisors is an integer number (156945600).

Almost surely, 2^21121962840 is an apocalyptic number.

21121962840 is a gapful number since it is divisible by the number (20) 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 21121962840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40178073600).

21121962840 is an abundant number, since it is smaller than the sum of its proper divisors (59234184360).

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

21121962840 is a wasteful number, since it uses less digits than its factorization.

21121962840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 836 (or 826 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The spelling of 21121962840 in words is "twenty-one billion, one hundred twenty-one million, nine hundred sixty-two thousand, eight hundred forty".