21551361510 has 256 divisors, whose sum is σ = 63239159808. Its totient is φ = 4596134400.

The previous prime is 21551361509. The next prime is 21551361551. The reversal of 21551361510 is 1516315512.

It is a super-2 number, since 2×21551361510² (a number of 21 digits) contains 22 as substring.

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 127 ways as a sum of consecutive naturals, for example, 31553629 + ... + 31554311.

It is an arithmetic number, because the mean of its divisors is an integer number (247027968).

Almost surely, 2^21551361510 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21551361510, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31619579904).

21551361510 is an abundant number, since it is smaller than the sum of its proper divisors (41687798298).

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

21551361510 is a wasteful number, since it uses less digits than its factorization.

21551361510 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 899.

The product of its (nonzero) digits is 4500, while the sum is 30.

The spelling of 21551361510 in words is "twenty-one billion, five hundred fifty-one million, three hundred sixty-one thousand, five hundred ten".