21511064550 has 48 divisors (see below), whose sum is σ = 53687291472. Its totient is φ = 5699740800.

The previous prime is 21511064527. The next prime is 21511064581. The reversal of 21511064550 is 5546011512.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 433161 + ... + 480260.

It is an arithmetic number, because the mean of its divisors is an integer number (1118485239).

Almost surely, 2^21511064550 is an apocalyptic number.

21511064550 is an abundant number, since it is smaller than the sum of its proper divisors (32176226922).

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

21511064550 is a wasteful number, since it uses less digits than its factorization.

21511064550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 913593 (or 913588 counting only the distinct ones).

The product of its (nonzero) digits is 6000, while the sum is 30.

The spelling of 21511064550 in words is "twenty-one billion, five hundred eleven million, sixty-four thousand, five hundred fifty".