21123542020346 has 4 divisors (see below), whose sum is σ = 31685313030522. Its totient is φ = 10561771010172.

The previous prime is 21123542020337. The next prime is 21123542020349. The reversal of 21123542020346 is 64302024532112.

It is a happy number.

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., 11147325015121 + 9976217005225 = 3338761^2 + 3158515^2 .

It is not an unprimeable number, because it can be changed into a prime (21123542020349) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5280885505085 + ... + 5280885505088.

Almost surely, 2^{21123542020346} is an apocalyptic number.

21123542020346 is a deficient number, since it is larger than the sum of its proper divisors (10561771010176).

21123542020346 is a wasteful number, since it uses less digits than its factorization.

21123542020346 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10561771010175.

The product of its (nonzero) digits is 69120, while the sum is 35.

Adding to 21123542020346 its reverse (64302024532112), we get a palindrome (85425566552458).

The spelling of 21123542020346 in words is "twenty-one trillion, one hundred twenty-three billion, five hundred forty-two million, twenty thousand, three hundred forty-six".