21982551 has 16 divisors (see below), whose sum is σ = 31144800. Its totient is φ = 13765248.

The previous prime is 21982537. The next prime is 21982567. The reversal of 21982551 is 15528912.

It is not a de Polignac number, because 21982551 - 2⁷ = 21982423 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21982531) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 196 + ... + 6633.

It is an arithmetic number, because the mean of its divisors is an integer number (1946550).

Almost surely, 2^21982551 is an apocalyptic number.

21982551 is a deficient number, since it is larger than the sum of its proper divisors (9162249).

21982551 is a wasteful number, since it uses less digits than its factorization.

21982551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6898.

The product of its digits is 7200, while the sum is 33.

The square root of 21982551 is about 4688.5553212050. Note that the first 3 decimals coincide. The cubic root of 21982551 is about 280.1298334955.

The spelling of 21982551 in words is "twenty-one million, nine hundred eighty-two thousand, five hundred fifty-one".