21021015157049 has 4 divisors (see below), whose sum is σ = 21022513141236. Its totient is φ = 21019517172864.

The previous prime is 21021015156983. The next prime is 21021015157081. The reversal of 21021015157049 is 94075151012012.

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 2 ways, for example, as 5341252543225 + 15679762613824 = 2311115^2 + 3959768^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021015157049 - 2²⁸ = 21020746721593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21021015151049) 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, 748971044 + ... + 748999109.

It is an arithmetic number, because the mean of its divisors is an integer number (5255628285309).

Almost surely, 2^{21021015157049} is an apocalyptic number.

It is an amenable number.

21021015157049 is a deficient number, since it is larger than the sum of its proper divisors (1497984187).

21021015157049 is a wasteful number, since it uses less digits than its factorization.

21021015157049 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1497984186.

The product of its (nonzero) digits is 25200, while the sum is 38.

The spelling of 21021015157049 in words is "twenty-one trillion, twenty-one billion, fifteen million, one hundred fifty-seven thousand, forty-nine".