21155651650 has 48 divisors (see below), whose sum is σ = 47337773760. Its totient is φ = 6871608000.

The previous prime is 21155651599. The next prime is 21155651659. The reversal of 21155651650 is 5615655112.

It is a super-2 number, since 2×21155651650² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21155651659) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1584001 + ... + 1597300.

It is an arithmetic number, because the mean of its divisors is an integer number (986203620).

Almost surely, 2^21155651650 is an apocalyptic number.

21155651650 is an abundant number, since it is smaller than the sum of its proper divisors (26182122110).

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

21155651650 is a wasteful number, since it uses less digits than its factorization.

21155651650 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3181339 (or 3181334 counting only the distinct ones).

The product of its (nonzero) digits is 45000, while the sum is 37.

The spelling of 21155651650 in words is "twenty-one billion, one hundred fifty-five million, six hundred fifty-one thousand, six hundred fifty".