21121533658 has 4 divisors (see below), whose sum is σ = 31682300490. Its totient is φ = 10560766828.

The previous prime is 21121533541. The next prime is 21121533661. The reversal of 21121533658 is 85633512112.

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

It can be written as a sum of positive squares in only one way, i.e., 20735136009 + 386397649 = 143997^2 + 19657^2 .

It is a super-2 number, since 2×21121533658² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5280383413 + ... + 5280383416.

Almost surely, 2^21121533658 is an apocalyptic number.

21121533658 is a deficient number, since it is larger than the sum of its proper divisors (10560766832).

21121533658 is a wasteful number, since it uses less digits than its factorization.

21121533658 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10560766831.

The product of its digits is 43200, while the sum is 37.

The spelling of 21121533658 in words is "twenty-one billion, one hundred twenty-one million, five hundred thirty-three thousand, six hundred fifty-eight".