20921260440 has 64 divisors (see below), whose sum is σ = 63647804160. Its totient is φ = 5500423040.

The previous prime is 20921260357. The next prime is 20921260441. The reversal of 20921260440 is 4406212902.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 20921260398 and 20921260407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20921260441) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1219254 + ... + 1236293.

It is an arithmetic number, because the mean of its divisors is an integer number (994496940).

Almost surely, 2^20921260440 is an apocalyptic number.

20921260440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20921260440 is an abundant number, since it is smaller than the sum of its proper divisors (42726543720).

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

20921260440 is a wasteful number, since it uses less digits than its factorization.

20921260440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2455632 (or 2455628 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 30.

The spelling of 20921260440 in words is "twenty billion, nine hundred twenty-one million, two hundred sixty thousand, four hundred forty".