21477844 has 6 divisors (see below), whose sum is σ = 37586234. Its totient is φ = 10738920.

The previous prime is 21477811. The next prime is 21477853. The reversal of 21477844 is 44877412.

It can be written as a sum of positive squares in only one way, i.e., 14348944 + 7128900 = 3788^2 + 2670^2 .

It is a super-2 number, since 2×21477844² = 922595565776672, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2684727 + ... + 2684734.

Almost surely, 2^21477844 is an apocalyptic number.

It is an amenable number.

21477844 is a deficient number, since it is larger than the sum of its proper divisors (16108390).

21477844 is a wasteful number, since it uses less digits than its factorization.

21477844 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5369465 (or 5369463 counting only the distinct ones).

The product of its digits is 50176, while the sum is 37.

The square root of 21477844 is about 4634.4194889975. The cubic root of 21477844 is about 277.9693391301.

The spelling of 21477844 in words is "twenty-one million, four hundred seventy-seven thousand, eight hundred forty-four".