21979782 has 32 divisors (see below), whose sum is σ = 53285760. Its totient is φ = 6660360.

The previous prime is 21979781. The next prime is 21979787. The reversal of 21979782 is 28797912.

It is a super-2 number, since 2×21979782² = 966221633535048, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21979781) 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, 17908 + ... + 19095.

It is an arithmetic number, because the mean of its divisors is an integer number (1665180).

Almost surely, 2^21979782 is an apocalyptic number.

21979782 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21979782 is an abundant number, since it is smaller than the sum of its proper divisors (31305978).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21979782 is a wasteful number, since it uses less digits than its factorization.

21979782 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37025 (or 37019 counting only the distinct ones).

The product of its digits is 127008, while the sum is 45.

The square root of 21979782 is about 4688.2600183864. The cubic root of 21979782 is about 280.1180709529.

The spelling of 21979782 in words is "twenty-one million, nine hundred seventy-nine thousand, seven hundred eighty-two".