21290065920 has 784 divisors, whose sum is σ = 82513700352. Its totient is φ = 5255331840.

The previous prime is 21290065891. The next prime is 21290065931. The reversal of 21290065920 is 2956009212.

It is a happy number.

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

It is an unprimeable number.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 686776305 + ... + 686776335.

Almost surely, 2^21290065920 is an apocalyptic number.

21290065920 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 21290065920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41256850176).

21290065920 is an abundant number, since it is smaller than the sum of its proper divisors (61223634432).

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

21290065920 is an frugal number, since it uses more digits than its factorization.

21290065920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103 (or 64 counting only the distinct ones).

The product of its (nonzero) digits is 19440, while the sum is 36.

The spelling of 21290065920 in words is "twenty-one billion, two hundred ninety million, sixty-five thousand, nine hundred twenty".