21531320776 has 32 divisors (see below), whose sum is σ = 47120221440. Its totient is φ = 9031373568.

The previous prime is 21531320689. The next prime is 21531320791. The reversal of 21531320776 is 67702313512.

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, 4087665 + ... + 4092928.

It is an arithmetic number, because the mean of its divisors is an integer number (1472506920).

Almost surely, 2^21531320776 is an apocalyptic number.

It is an amenable number.

21531320776 is an abundant number, since it is smaller than the sum of its proper divisors (25588900664).

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

21531320776 is a wasteful number, since it uses less digits than its factorization.

21531320776 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8180653 (or 8180649 counting only the distinct ones).

The product of its (nonzero) digits is 52920, while the sum is 37.

The spelling of 21531320776 in words is "twenty-one billion, five hundred thirty-one million, three hundred twenty thousand, seven hundred seventy-six".