21651982 has 48 divisors (see below), whose sum is σ = 39931920. Its totient is φ = 8743680.

The previous prime is 21651979. The next prime is 21651989. The reversal of 21651982 is 28915612.

It is a Harshad number since it is a multiple of its sum of digits (34).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21651989) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 78028 + ... + 78304.

It is an arithmetic number, because the mean of its divisors is an integer number (831915).

Almost surely, 2^21651982 is an apocalyptic number.

21651982 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21651982 is a deficient number, since it is larger than the sum of its proper divisors (18279938).

21651982 is a wasteful number, since it uses less digits than its factorization.

21651982 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 337 (or 326 counting only the distinct ones).

The product of its digits is 8640, while the sum is 34.

The square root of 21651982 is about 4653.1690276628. The cubic root of 21651982 is about 278.7185575882.

The spelling of 21651982 in words is "twenty-one million, six hundred fifty-one thousand, nine hundred eighty-two".