21167979 has 16 divisors (see below), whose sum is σ = 32514048. Its totient is φ = 11999232.

The previous prime is 21167969. The next prime is 21167987. The reversal of 21167979 is 97976112.

It is a happy number.

It is not a de Polignac number, because 21167979 - 2⁴ = 21167963 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21167979.

It is not an unprimeable number, because it can be changed into a prime (21167929) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1302 + ... + 6635.

It is an arithmetic number, because the mean of its divisors is an integer number (2032128).

Almost surely, 2^21167979 is an apocalyptic number.

21167979 is a deficient number, since it is larger than the sum of its proper divisors (11346069).

21167979 is a wasteful number, since it uses less digits than its factorization.

21167979 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8074.

The product of its digits is 47628, while the sum is 42.

The square root of 21167979 is about 4600.8672008655. The cubic root of 21167979 is about 276.6260860466.

The spelling of 21167979 in words is "twenty-one million, one hundred sixty-seven thousand, nine hundred seventy-nine".