21512245545 has 64 divisors (see below), whose sum is σ = 43739043840. Its totient is φ = 9827054784.

The previous prime is 21512245541. The next prime is 21512245549. The reversal of 21512245545 is 54554221512.

21512245545 is a `hidden beast` number, since 2 + 1 + 51 + 22 + 45 + 545 = 666.

It is an interprime number because it is at equal distance from previous prime (21512245541) and next prime (21512245549).

It is not a de Polignac number, because 21512245545 - 2² = 21512245541 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21512245541) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1431762 + ... + 1446708.

It is an arithmetic number, because the mean of its divisors is an integer number (683422560).

Almost surely, 2^21512245545 is an apocalyptic number.

It is an amenable number.

21512245545 is an abundant number, since it is smaller than the sum of its proper divisors (22226798295).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21512245545 is a wasteful number, since it uses less digits than its factorization.

21512245545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16491 (or 16485 counting only the distinct ones).

The product of its digits is 80000, while the sum is 36.

The spelling of 21512245545 in words is "twenty-one billion, five hundred twelve million, two hundred forty-five thousand, five hundred forty-five".