21770740 has 12 divisors (see below), whose sum is σ = 45718596. Its totient is φ = 8708288.

The previous prime is 21770731. The next prime is 21770747. The reversal of 21770740 is 4707712.

It can be written as a sum of positive squares in 2 ways, for example, as 13162384 + 8608356 = 3628^2 + 2934^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21770699 and 21770708.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21770747) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 544249 + ... + 544288.

It is an arithmetic number, because the mean of its divisors is an integer number (3809883).

Almost surely, 2^21770740 is an apocalyptic number.

21770740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21770740 is an abundant number, since it is smaller than the sum of its proper divisors (23947856).

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

21770740 is a wasteful number, since it uses less digits than its factorization.

21770740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1088546 (or 1088544 counting only the distinct ones).

The product of its (nonzero) digits is 2744, while the sum is 28.

The square root of 21770740 is about 4665.9125581177. The cubic root of 21770740 is about 279.2272058010.

The spelling of 21770740 in words is "twenty-one million, seven hundred seventy thousand, seven hundred forty".