21982155 has 32 divisors (see below), whose sum is σ = 38196480. Its totient is φ = 10730880.

The previous prime is 21982151. The next prime is 21982171. The reversal of 21982155 is 55128912.

It is not a de Polignac number, because 21982155 - 2² = 21982151 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21982151) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 26700 + ... + 27510.

It is an arithmetic number, because the mean of its divisors is an integer number (1193640).

Almost surely, 2^21982155 is an apocalyptic number.

21982155 is a deficient number, since it is larger than the sum of its proper divisors (16214325).

21982155 is a wasteful number, since it uses less digits than its factorization.

21982155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 971.

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

The square root of 21982155 is about 4688.5130905224. The cubic root of 21982155 is about 280.1281513723.

The spelling of 21982155 in words is "twenty-one million, nine hundred eighty-two thousand, one hundred fifty-five".