21501651850 has 48 divisors (see below), whose sum is σ = 48394991808. Its totient is φ = 6938346240.

The previous prime is 21501651841. The next prime is 21501651851. The reversal of 21501651850 is 5815610512.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is not an unprimeable number, because it can be changed into a prime (21501651851) 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, 1800912 + ... + 1812811.

It is an arithmetic number, because the mean of its divisors is an integer number (1008228996).

Almost surely, 2^21501651850 is an apocalyptic number.

21501651850 is an abundant number, since it is smaller than the sum of its proper divisors (26893339958).

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

21501651850 is a wasteful number, since it uses less digits than its factorization.

21501651850 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3613759 (or 3613754 counting only the distinct ones).

The product of its (nonzero) digits is 12000, while the sum is 34.

The spelling of 21501651850 in words is "twenty-one billion, five hundred one million, six hundred fifty-one thousand, eight hundred fifty".