21037740 has 24 divisors (see below), whose sum is σ = 58905840. Its totient is φ = 5610048.

The previous prime is 21037739. The next prime is 21037771. The reversal of 21037740 is 4773012.

It is a self number, because there is not a number n which added to its sum of digits gives 21037740.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 175255 + ... + 175374.

It is an arithmetic number, because the mean of its divisors is an integer number (2454410).

Almost surely, 2^21037740 is an apocalyptic number.

21037740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21037740 is an abundant number, since it is smaller than the sum of its proper divisors (37868100).

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

21037740 is a wasteful number, since it uses less digits than its factorization.

21037740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 350641 (or 350639 counting only the distinct ones).

The product of its (nonzero) digits is 1176, while the sum is 24.

The square root of 21037740 is about 4586.6916181492. The cubic root of 21037740 is about 276.0575914265.

It can be divided in two parts, 210 and 37740, that added together give a triangular number (37950 = T₂₇₅).

The spelling of 21037740 in words is "twenty-one million, thirty-seven thousand, seven hundred forty".