61421216537 has 4 divisors (see below), whose sum is σ = 61421713716. Its totient is φ = 61420719360.

The previous prime is 61421216509. The next prime is 61421216539. The reversal of 61421216537 is 73561212416.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 8062064521 + 53359152016 = 89789^2 + 230996^2 .

It is a cyclic number.

It is not a de Polignac number, because 61421216537 - 2²⁴ = 61404439321 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 61421216537.

It is not an unprimeable number, because it can be changed into a prime (61421216539) 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, 95237 + ... + 363197.

It is an arithmetic number, because the mean of its divisors is an integer number (15355428429).

Almost surely, 2^61421216537 is an apocalyptic number.

It is an amenable number.

61421216537 is a deficient number, since it is larger than the sum of its proper divisors (497179).

61421216537 is a wasteful number, since it uses less digits than its factorization.

61421216537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 497178.

The product of its digits is 60480, while the sum is 38.

The spelling of 61421216537 in words is "sixty-one billion, four hundred twenty-one million, two hundred sixteen thousand, five hundred thirty-seven".