21661016700 has 36 divisors (see below), whose sum is σ = 62672542520. Its totient is φ = 5776271040.

The previous prime is 21661016677. The next prime is 21661016791. The reversal of 21661016700 is 761016612.

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 11 ways as a sum of consecutive naturals, for example, 36101395 + ... + 36101994.

Almost surely, 2^21661016700 is an apocalyptic number.

21661016700 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21661016700 is an abundant number, since it is smaller than the sum of its proper divisors (41011525820).

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

21661016700 is a wasteful number, since it uses less digits than its factorization.

21661016700 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72203406 (or 72203399 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 30.

The spelling of 21661016700 in words is "twenty-one billion, six hundred sixty-one million, sixteen thousand, seven hundred".