21371247739 has 4 divisors (see below), whose sum is σ = 21372722856. Its totient is φ = 21369772624.

The previous prime is 21371247713. The next prime is 21371247761. The reversal of 21371247739 is 93774217312.

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

It is a cyclic number.

It is not a de Polignac number, because 21371247739 - 2²³ = 21362859131 is a prime.

It is a super-2 number, since 2×21371247739² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21371247769) 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, 715609 + ... + 744874.

It is an arithmetic number, because the mean of its divisors is an integer number (5343180714).

Almost surely, 2^21371247739 is an apocalyptic number.

21371247739 is a deficient number, since it is larger than the sum of its proper divisors (1475117).

21371247739 is a wasteful number, since it uses less digits than its factorization.

21371247739 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1475116.

The product of its digits is 444528, while the sum is 46.

The spelling of 21371247739 in words is "twenty-one billion, three hundred seventy-one million, two hundred forty-seven thousand, seven hundred thirty-nine".