21370756538 has 4 divisors (see below), whose sum is σ = 32056134810. Its totient is φ = 10685378268.

The previous prime is 21370756523. The next prime is 21370756553. The reversal of 21370756538 is 83565707312.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21370756523) and next prime (21370756553).

It can be written as a sum of positive squares in only one way, i.e., 17459129689 + 3911626849 = 132133^2 + 62543^2 .

It is a super-4 number, since 4×21370756538⁴ (a number of 42 digits) contains 4444 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21370756492 and 21370756501.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5342689133 + ... + 5342689136.

Almost surely, 2^21370756538 is an apocalyptic number.

21370756538 is a deficient number, since it is larger than the sum of its proper divisors (10685378272).

21370756538 is a wasteful number, since it uses less digits than its factorization.

21370756538 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10685378271.

The product of its (nonzero) digits is 1058400, while the sum is 47.

The spelling of 21370756538 in words is "twenty-one billion, three hundred seventy million, seven hundred fifty-six thousand, five hundred thirty-eight".