21047551077 has 32 divisors (see below), whose sum is σ = 32221635840. Its totient is φ = 11971330560.

The previous prime is 21047551061. The next prime is 21047551087. The reversal of 21047551077 is 77015574012.

It is a happy number.

It is not a de Polignac number, because 21047551077 - 2⁴ = 21047551061 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21047551037) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 8808999 + ... + 8811387.

It is an arithmetic number, because the mean of its divisors is an integer number (1006926120).

Almost surely, 2^21047551077 is an apocalyptic number.

It is an amenable number.

21047551077 is a deficient number, since it is larger than the sum of its proper divisors (11174084763).

21047551077 is a wasteful number, since it uses less digits than its factorization.

21047551077 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4173.

The product of its (nonzero) digits is 68600, while the sum is 39.

The spelling of 21047551077 in words is "twenty-one billion, forty-seven million, five hundred fifty-one thousand, seventy-seven".