21897582440 has 32 divisors (see below), whose sum is σ = 49332235680. Its totient is φ = 8747890752.

The previous prime is 21897582439. The next prime is 21897582491. The reversal of 21897582440 is 4428579812.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 316322 + ... + 379281.

It is an arithmetic number, because the mean of its divisors is an integer number (1541632365).

Almost surely, 2^21897582440 is an apocalyptic number.

21897582440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21897582440 is an abundant number, since it is smaller than the sum of its proper divisors (27434653240).

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

21897582440 is a wasteful number, since it uses less digits than its factorization.

21897582440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 696401 (or 696397 counting only the distinct ones).

The product of its (nonzero) digits is 1290240, while the sum is 50.

The spelling of 21897582440 in words is "twenty-one billion, eight hundred ninety-seven million, five hundred eighty-two thousand, four hundred forty".