211721992251 has 48 divisors (see below), whose sum is σ = 355252031232. Its totient is φ = 109789352640.

The previous prime is 211721992243. The next prime is 211721992343. The reversal of 211721992251 is 152299127112.

It is not a de Polignac number, because 211721992251 - 2³ = 211721992243 is a prime.

It is not an unprimeable number, because it can be changed into a prime (211721992201) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1356585 + ... + 1504581.

It is an arithmetic number, because the mean of its divisors is an integer number (7401083984).

Almost surely, 2^211721992251 is an apocalyptic number.

211721992251 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

211721992251 is a deficient number, since it is larger than the sum of its proper divisors (143530038981).

211721992251 is a wasteful number, since it uses less digits than its factorization.

211721992251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 148592 (or 148581 counting only the distinct ones).

The product of its digits is 45360, while the sum is 42.

The spelling of 211721992251 in words is "two hundred eleven billion, seven hundred twenty-one million, nine hundred ninety-two thousand, two hundred fifty-one".