21977740 has 24 divisors (see below), whose sum is σ = 46252080. Its totient is φ = 8772288.

The previous prime is 21977713. The next prime is 21977743. The reversal of 21977740 is 4777912.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21977740.

It is not an unprimeable number, because it can be changed into a prime (21977743) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12006 + ... + 13714.

It is an arithmetic number, because the mean of its divisors is an integer number (1927170).

Almost surely, 2^21977740 is an apocalyptic number.

21977740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21977740 is an abundant number, since it is smaller than the sum of its proper divisors (24274340).

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

21977740 is a wasteful number, since it uses less digits than its factorization.

21977740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2361 (or 2359 counting only the distinct ones).

The product of its (nonzero) digits is 24696, while the sum is 37.

The square root of 21977740 is about 4688.0422353046. The cubic root of 21977740 is about 280.1093960289.

The spelling of 21977740 in words is "twenty-one million, nine hundred seventy-seven thousand, seven hundred forty".