21537425520077 has 4 divisors (see below), whose sum is σ = 22670974231680. Its totient is φ = 20403876808476.

The previous prime is 21537425520071. The next prime is 21537425520101. The reversal of 21537425520077 is 77002552473512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21537425520077 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21537425520071) 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, 566774355773 + ... + 566774355810.

It is an arithmetic number, because the mean of its divisors is an integer number (5667743557920).

Almost surely, 2^{21537425520077} is an apocalyptic number.

It is an amenable number.

21537425520077 is a deficient number, since it is larger than the sum of its proper divisors (1133548711603).

21537425520077 is a wasteful number, since it uses less digits than its factorization.

21537425520077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1133548711602.

The product of its (nonzero) digits is 4116000, while the sum is 50.

Adding to 21537425520077 its reverse (77002552473512), we get a palindrome (98539977993589).

The spelling of 21537425520077 in words is "twenty-one trillion, five hundred thirty-seven billion, four hundred twenty-five million, five hundred twenty thousand, seventy-seven".