210221999956 has 12 divisors (see below), whose sum is σ = 369632048800. Its totient is φ = 104612843160.

The previous prime is 210221999903. The next prime is 210221999959. The reversal of 210221999956 is 659999122012.

It is a hoax number, since the sum of its digits (55) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 210221999897 and 210221999906.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (210221999959) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 124538256 + ... + 124539943.

Almost surely, 2^210221999956 is an apocalyptic number.

It is an amenable number.

210221999956 is a deficient number, since it is larger than the sum of its proper divisors (159410048844).

210221999956 is a wasteful number, since it uses less digits than its factorization.

210221999956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249078414 (or 249078412 counting only the distinct ones).

The product of its (nonzero) digits is 1574640, while the sum is 55.

The spelling of 210221999956 in words is "two hundred ten billion, two hundred twenty-one million, nine hundred ninety-nine thousand, nine hundred fifty-six".