21237764 has 6 divisors (see below), whose sum is σ = 37166094. Its totient is φ = 10618880.

The previous prime is 21237761. The next prime is 21237767. The reversal of 21237764 is 46773212.

It is an interprime number because it is at equal distance from previous prime (21237761) and next prime (21237767).

It can be written as a sum of positive squares in only one way, i.e., 20775364 + 462400 = 4558^2 + 680^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21237764.

It is not an unprimeable number, because it can be changed into a prime (21237761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2654717 + ... + 2654724.

It is an arithmetic number, because the mean of its divisors is an integer number (6194349).

Almost surely, 2^21237764 is an apocalyptic number.

It is an amenable number.

21237764 is a deficient number, since it is larger than the sum of its proper divisors (15928330).

21237764 is a wasteful number, since it uses less digits than its factorization.

21237764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5309445 (or 5309443 counting only the distinct ones).

The product of its digits is 14112, while the sum is 32.

The square root of 21237764 is about 4608.4448569989. Note that the first 3 decimals coincide. The cubic root of 21237764 is about 276.9297392905.

The spelling of 21237764 in words is "twenty-one million, two hundred thirty-seven thousand, seven hundred sixty-four".